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Marine predators use prey handling behaviors that are best suited to the proper- ties (e.g., size, shape, and texture) of the prey species being targeted (Hocking et al. 2016, 2017). Predators that target large prey species that cannot be swal- lowed whole are required to process prey extensively before consumption (either breaking it into smaller pieces or softening it). For example, crocodiles and alliga- tors perform a spinning “death roll” to dismember large prey items (Fish et al. 2007). Leopard seals (Hydrurga leptonyx) thrash sea birds and seal pups to break them into edible pieces (Edwards et al. 2010). Australian fur seals (Arctocephalus pusillus doriferus) shake and toss large fish and cephalopods before consumption (Hocking et al. 2016). Similarly, for toothed whales, if prey items are too large to swallow whole they also need to spend time processing prey. For example, killer whales (Orcinus orca) shake sea lions and beluga whales (Delphinapterus leucas) (Lopez and Lopez 1985, Frost et al. 1992), and toss dusky dolphins (Lagenor- hynchus obscurus) and stingrays into the air (Constantine et al. 1998, Visser 1999). Bottlenose dolphins (Tursiops spp.) shake and toss fish to break them into smaller pieces and to soften them for ease of consumption (W€ursig and W€ursig 1979, Shane 1990). Bottlenose dolphins also use complex prey handling to break giant cuttlefish (Sepia apama) into manageable pieces, using a sequence of steps to remove the head, ink, and cuttlebone before the flesh of the mantle is consumed (Finn et al. 2009, Smith and Sprogis 2016). Prey handling behaviors vary among species and locations and are influenced by the availability of prey species. In this study, we describe the complex prey handling behavior of benthic octopus by T. aduncus in southwestern Australia. We investigate whether this behavior is (1) associated with specific ecological variables, (2) is age- or sex-specific, and (3) is a socially learned behavior.
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MARINE MAMMAL SCIENCE, 33(3): 934–945 (July 2017)
©2017 Society for Marine Mammalogy
DOI: 10.1111/mms.12405
Complex prey handling of octopus by bottlenose dolphins
(Tursiops aduncus)
Murdoch University Cetacean Research Unit, School of Veterinary and
Life Sciences, Murdoch University, Perth, Western Australia 6150, Australia; HOLLY C.
Murdoch University Cetacean Research Unit, School of Veterinary and Life
Sciences, Murdoch University, Perth, Western Australia 6150, Australia and Marine Science
Program, Department of Parks and Wildlife, Perth, Western Australia 6151, Australia;
DAVID HOCKING,School of Biological Sciences, Monash University, Melbourne, Victoria
3800, Australia; LARS BEJDER,Murdoch University Cetacean Research Unit, School of
Veterinary and Life Sciences, Murdoch University, Perth, Western Australia 6150, Australia.
Marine predators use prey handling behaviors that are best suited to the proper-
ties (e.g., size, shape, and texture) of the prey species being targeted (Hocking
et al. 2016, 2017). Predators that target large prey species that cannot be swal-
lowed whole are required to process prey extensively before consumption (either
breaking it into smaller pieces or softening it). For example, crocodiles and alliga-
tors perform a spinning “death roll” to dismember large prey items (Fish et al.
2007). Leopard seals (Hydrurga leptonyx) thrash sea birds and seal pups to break
them into edible pieces (Edwards et al. 2010). Australian fur seals (Arctocephalus
pusillus doriferus) shake and toss large fish and cephalopods before consumption
(Hocking et al. 2016). Similarly, for toothed whales, if prey items are too large to
swallow whole they also need to spend time processing prey. For example, killer
whales (Orcinus orca) shake sea lions and beluga whales (Delphinapterus leucas)
(Lopez and Lopez 1985, Frost et al. 1992), and toss dusky dolphins (Lagenor-
hynchus obscurus) and stingrays into the air (Constantine et al. 1998, Visser 1999).
Bottlenose dolphins (Tursiops spp.) shake and toss fish to break them into smaller
pieces and to soften them for ease of consumption (Wursig and Wursig 1979,
Shane 1990). Bottlenose dolphins also use complex prey handling to break giant
cuttlefish (Sepia apama) into manageable pieces, using a sequence of steps to
remove the head, ink, and cuttlebone before the flesh of the mantle is consumed
Corresponding author (e-mail:
nee Smith.
(Finn et al. 2009, Smith and Sprogis 2016). Prey handling behaviors vary among
species and locations and are influenced by the availability of prey species.
Within a population, foraging for specific prey may be linked with ecological vari-
ables, age- and/or sex, and/or be socially learned from conspecifics (Weiss 2006, Sar-
geant et al. 2007, Torres and Read 2009, Patterson et al. 2016). For example, in
Shark Bay, Western Australia, “sponging” is a solitary foraging specialization where
predominantly adult female bottlenose dolphins (T. aduncus)useamarinespongeon
their rostrum as a protective tool to probe the seafloor to feed on burrowing fish (Pat-
terson and Mann 2011). Sponging is linked to specific environments, being mainly
employed in deep-water channels (>10 m) where conical marine sponges occur (Sar-
geant et al. 2007, Tyne et al. 2012). This foraging tactic is also vertically transmitted
from mother to female offspring (Krutzen et al. 2005), and requires an extensive
period of exposure to promote calf learning (Mann et al. 2008). Similarly to foraging
tactics, prey handling behaviors may also be linked to ecological variables, be
age/sex-specific, or socially learned from conspecifics.
In this study, we describe the complex prey handling behavior of benthic octopus
by T. aduncus in southwestern Australia. We investigate whether this behavior is (1)
associated with specific ecological variables, (2) is age- or sex-specific, and (3) is a
socially learned behavior.
The study region encompassed a 540 km
area in the temperate waters off Bunbury
(33°320S, 115°630E), Western Australia. Water depth ranged from <1 m in estuarine
waters and up to 24 m in open coastal waters. Data were collected year-round from
March 2007 to August 2013, and field methods were the same as for Sprogis et al.
(2016b). Boat-based, photographic-identification surveys of dolphins were conducted
along systematic line transects. Once dolphins were sighted, a dolphin group encoun-
ter began and photographs were taken of dolphin dorsal fins for identification pur-
poses (Wursig and Wursig 1977). The Global Positioning System (GPS) location,
depth, water temperature, turbidity (secchi depth), and dolphin group size were
recorded. During the first five minutes, the predominant group behavioral state (the
behavioral state that >50% of the group was engaged in) was recorded (i.e., foraging,
feeding, resting, socializing, travelling). During encounters, photographs of dolphins
handling octopus at the surface were taken and details were recorded (time, number
of tosses, and dolphin identification). Data were available on individual dolphins (in-
cluding sex and age class) from a long-term research program focused on the Bunbury
dolphin population (Smith et al. 2013, 2016; Sprogis et al. 2016a,b).
To explore if there was a relationship between octopus handling events and habitat
type, a benthic habitat map was created following Sprogis (2015). High-resolution
satellite imagery was validated via 185 validation points following the drop-down
camera methods described in Tyne et al. (2010). Each validation point was rated post
hoc for the percentage of habitat cover following Kohler and Gill (2006). To discrimi-
nate between benthic habitat types, a k-means unsupervised classification was con-
ducted and habitats were clustered into eight classes; reef, sand, seagrass, deep waters,
algae/reef, algae/sand, mud/sand, and mud/silt.
We explored whether octopus handling might be a socially transmitted behavior
by quantifying association histories of individual dolphins observed engaging in these
events over a 7 yr period. To test for preferred/avoided associations, association
indices between individuals were calculated to estimate the proportion of time they
were sighted together (Whitehead 2008). Pairs of individuals were assumed to be
associated if they were sighted in the same group. A group wasdenedasoneormore
dolphins within 100 m of other individuals and behaving similarly (Irvine et al.
1981, Wells et al. 1987). The simple ratio index (SRI, Ginsberg and Young 1992)
was used as we expected each individual to have an equal chance of being identified.
Association index values range from zero (never sighted together) to one (always
sighted together), and were calculated between (1) dolphins that were observed han-
dling octopus and (2) dolphins observed handling octopus with dolphins that were
not observed with octopus.
We tested for preferred/avoided associations using permutation analyses, where
the data were randomized multiple times (two-sided significance level =0.05,
Bejder et al. 1998, Whitehead et al. 2005). Analyses were run using SOCPROG
2.7 (Whitehead 2009) and only included dolphins that were sighted 5occasions.
The sampling period was set to five days, which was based on the mean number
of days needed to complete all transects in the main study area to optimize equal
probability of encountering individual dolphins (Sprogis et al. 2016a). To test
whether the observed data differed significantly from random, we determined the
number of permutations required to obtain an accurate P-value by increasing the
number of permutations (maximum 20,000) until the P-value stabilized (Bejder
et al. 1998), with 1,0005,000 trials per permutation. To examine the strength of
associations between individual dolphins we compared the SRI values against the
randomly generated values. For long-term associations (between sampling periods)
the null hypothesis was rejected if the standard deviation (SD) and coefficient of
variation (CV) of the observed SRI value was significantly higher (P<0.05) than
the SD and CV of the randomly permuted data (Whitehead et al. 2005, White-
head 2008).
Our study resulted in 587 surveys completed with homogenous sampling effort
across seasons (Table S1), with 177 surveys conducted within bay and estuarine
waters and 410 surveys in open coastal waters (Table S2). A total of 1,567 dolphin
groups were sighted and photographed (Table S1). We observed 45 octopus handling
events, with 33 of these observed while on survey effort. Handling events occurred
during separate group encounters, apart from one group encounter where three differ-
ent individuals in the same group were observed handling octopus.
Dolphins were observed handling octopus using two different methods (Fig. 1,
Movie S1, Fig. S1). The first method (shake) involved dolphins arching and rotating
their body out of the water, while holding the octopus in the jaws and forcefully hit-
ting it onto the surface of the water (Fig. 1d, Movie S1). The second method (toss)
involved the dolphins also raising their head and/or body out of the water and flick-
ing the octopus out of the water, but instead of keeping their jaws closed, they
opened their mouths so that the octopus was released and tossed into the air, often
travelling over several meters (Fig. 1, Movie S1). The dolphin would subsequently
retrieve the octopus and continue to shake and toss it at the surface (commonly 10
15 times). In some cases, a “shake” became a “toss” if the prey item tore and frag-
mented during the shake, and hence was then thrown across the water rather than
being hit onto the water’s surface.
The observed octopus handling events lasted from <1 min to >6min.Insome
instances, octopus handling had already commenced when dolphins were sighted, so
these are considered minimum durations for dolphins to process octopus. No observa-
tions were made underwater; therefore, it was not possible to determine whether any
processing occurred below the surface. Generally, the head and the mantle of the
octopus was removed prior to our observations, making it difficult to identify octopus
to the species level. We were not able to retrieve any octopus parts during sightings
for species verification.
Octopus handling events occurred throughout all seasons (Poisson generalized lin-
ear model, P=0.05), with the majority of sightings in winter and spring (Fig. 2).
Events took place in water temperatures ranging from 14.4°C to 23.3°C(x=18.4°C
0.47 SE, Fig. 2). Sightings were in water depths between 0.8 m and 14.7 m
(x=9.09 m 0.66 SE) and in waters with a turbidity ranging from 0.8 to 10 m
(x=3.30 m 0.38 SE). Events took place predominantly over sand, algae/sand, and
mud/silt habitats (33.3%, 21.2%, 21.2%, respectively; Fig. 3).
Of the 33 octopus handling events observed while on survey, six dolphins were
unable to be identified and 26 were known from our photo-identification catalogue
(with one individual observed handling octopus on two occasions). Of these known
Figure 1. A sequence of an octopus handling event by an adult male bottlenose dolphin off
Bunbury, Western Australia. This event lasted for approximately 5 min, with 12 octopus
shakes and/or tosses observed. Each row (af) represents consecutive actions, displaying exam-
ples of the different types of handling methods: shaking (d) and tossing (a, b, c, e, f).
dolphins, 20 were adults, 4 were juveniles, and 2 were calves. Sex was determined for
14 females and 4 males, while 8 animals were of unknown sex. The mean group size
of all encountered dolphin groups was 5.98 (0.14 SD, range 145 dolphins,
Table S1). For foraging and feeding groups, mean group size was 4.38 (4.41 SD) and
4.82 (7.09 SD), respectively (Table S3). For octopus handling events, the mean group
size was 9.55 (9.55 SD, range =136 dolphins). Octopus handling was observed in
conjunction with all group behavioral activities, with traveling and feeding groups
the most likely groups to observe a dolphin handling octopus (30.3% and 27.3% of
the events, respectively).
Of the 26 dolphins identified handling octopus, 25 were sighted on five or more
occasions and were used in the permutation analyses. Over the long-term (between
sampling periods), there was indication of long-term preferred associations between
dolphins that handled octopus, as both the observed SD and CV of the SRI were
significantly higher than the randomized SD (observed =0.052, randomized =
0.048, P=<0.0001) and CV (observed =1.605, randomized =1.500, P=0.0001),
with 8 pairs among 25 dolphins (dyadic P>0.97).
Associations were tested between the 25 dolphins handling octopus and the
remaining 280 dolphins in the population that met the threshold of five or more
occasions. For long-term associations, both the observed SD and CV of the SRI were
significantly higher than the randomized SD (observed =0.049, randomized =
0.042, P=0.0001) and CV (observed =2.404, randomized =2.110, P=<0.0001),
indicating the occurrence of preferred (189 pairs, dyadic P>0.975) and avoided asso-
ciations (50 pairs, dyadic P<0.025).
The behavior of octopus handling (shaking and tossing) is previously undescribed.
We suggest that T. aduncus shake octopus forcefully onto the water’s surface and toss
octopus several meters into the air multiple times to (1) remove the octopus head and
mantle, (2) tenderize and ensure the arms are inactive, and (3) break the octopus into
smaller pieces for easier consumption. We documented that octopus handling behav-
ior (1) was a seasonal occurrence, peaking during winter and spring in water
Figure 2. The cumulative number of octopus handling events (gray bars, n=33) and the
mean sea surface temperature (black dots) during each austral season between Autumn 2007
and Spring 2013. Continuity between dots is not implied.
temperatures around 18°C, (2) was most prevalent among adult females, and (3) was
conducted by dolphins that showed a close association with other dolphins that han-
dled octopus.
Figure 3. Locations of octopus handling events (black circles, n=33) by Indo-Pacific bot-
tlenose dolphins off Bunbury, Western Australia, over benthic habitat consisting of sand,
algae/sand, and mud/silt, and seagrass.
Octopus can be difficult for dolphins to handle (see dos Santos and Lacerda 1987,
Orbach and Kirchner 2014), and in our study area dolphins were required to arch
their head and/or body out of the water in order to shake or toss octopus clear of the
water. As a result, this handling method involves a large body movement that is
likely energetically expensive. Although more energetically demanding, this complex
prey handling behavior allows dolphins to process large prey type that may be risky
to consume without processing (dos Santos and Lacerda 1987).
It is apparent that octopus handling is a risky behavior, as within our study area a
known adult male stranded and a necropsy confirmed the cause of death was from
suffocation from a large 2.1 kg octopus.
The dolphin had attempted to swallow the
octopus, however, the octopus was found almost intact, with the head and the mantle
of the octopus in the dolphin’s stomach and the 1.3 m long arms separated from the
head and extending out of its mouth.
Similarly, another T. aduncus died from sus-
pected asphyxiation due to an octopus lodged in its mouth and pharynx approxi-
mately 140 km north of our study area (Shoalwater Bay Islands Marine Park).
these two cases, the dolphins may not have processed the octopus sufficiently by shak-
ing and tossing it to ensure the arm’s reflex withdrawal responses were inactive. Octo-
pus arms have a defensive response, as their receptors can detect stimuli that cause
damage to their tissues (Hague et al. 2013). These receptors allow octopus arms to
continue reacting even after the arms have been detached from the head, allowing the
arms to coordinate a reflex withdrawal response (Hague et al. 2013). Dolphins must
therefore process the octopus sufficiently to reduce the arms reflex withdrawal
response and limit their suckers adhering to them, which otherwise would make
them difficult to swallow.
The species of octopus that the dolphin suffocated on in Bunbury was identified as
the benthic-dwelling Maori octopus (Macroctopus maorum).
This octopus is robust
and muscular, and is the largest octopus found in Australasia weighing >10 kg with
an arm span of over 3 m (Norman 1999, Norman and Reid 2000). It occurs over soft
sediment and reefs where it occupies rocky lairs (Anderson 1999, Norman and Reid
2000). Other octopus species found within the study area are the common Perth octo-
pus (Octopus (cf.) tetricus) and the velvet octopus (Grimpella thaumastocheir).
The com-
mon Perth octopus is medium sized (mean 4 kg; Joll 1976) and inhabits rocky reefs,
seagrass meadows and sandy substrates (Hart et al. 2016). The velvet octopus is a
smaller species that has an arm span <60 cm (Norman and Reid 2000) and has been
caught in traps in Bunbury inner waters (McCluskey et al. 2016). Due to the larger
size of octopus observed during feeding events, dolphins off Bunbury are most likely
handling the Maori and common Perth octopus.
Octopus handling events occurred more often during winter and spring when the
water temperature reached approximately 18°C (Fig. 2). Although the ecology of the
Maori octopus is poorly understood in Western Australia, in New Zealand the mat-
ing period for this octopus is in spring with the optimal water temperature for eggs
to hatch at 18°C (Anderson 1999). Similarly, the optimal water temperature for the
eggs of the common Perth octopus to hatch is under 22°C(Hartet al. 2016). How-
ever, the common Perth octopus has no distinct mating period and they are able to
Unpublished data, Nahiid Stephens, veterinary pathologist, Murdoch University Cetacean Research
Unit, School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia.
Personal communication from Douglas Coughran, Department of Parks and Wildlife, Perth,
Australia. 2 September 2015.
Personal communication from Stephen Leporati, SCS Global Services, 19 October 2015.
spawn throughout the year (Hart et al. 2016). Octopus are semelparous, once
males mate and females brood their eggs they become senescent until their death
(Anderson et al. 2002). Senescence occurs for approximately one month, during
which octopus have uncoordinated movements, suboptimal camouflage abilities
and a deteriorating physical condition. Senescence may put octopus in a compro-
mised state, increasing their risk of predation (Anderson et al. 2002). As such, it
is likely that the opportunity for dolphins to capture octopus is increased in win-
ter and spring.
Octopus handling events occurred, on average, in 9 m depth and in turbid (x=
3.30 m) waters, predominantly over sand, algae/sand, and mud/silt habitat types. As
benthic habitat type in Bunbury is highly heterogeneous it was difficult to determine
exactly which habitat octopus were captured from. Furthermore, the octopus species
found off Bunbury occur over a range of habitats, therefore the capture of octopus
appears to be opportunistic over various habitats.
The majority of dolphins handling octopus were adults (20 of the 26 identified
dolphins), suggesting that there may be differences in physical abilities and/or learn-
ing experiences between adults and juveniles/calves. Similarly, in the case of foraging
tactics, bottlenose dolphins generally show differences between ages, which may
reflect energy requirements throughout life history stages and/or reflect a required
learning period (Patterson et al. 2016). In addition, of the adults observed handling
octopus (n=20), 60% were female and 20% were male (20% unknown sex). Thus,
adult females were the most prevalent age-sex class to handle octopus, however, more
data are needed to confirm that this sex-specific finding is not an artefact of females
having smaller home ranges (Sprogis et al. 2016b), and therefore being observed more
frequently throughout the year than males (Sprogis et al. 2016a).
Group size for octopus handling events was nearly twice the average group size for
feeding and foraging groups. Bottlenose dolphins are known to be a highly social
species (Connor et al. 2000), and in our study area adult females display low-level
associations among a large number of females and these associations re-form season-
ally (Smith et al. 2016). Adult males exhibit strong bonds with other adult males
(Sprogis et al. 2016a). Given their social nature, we explored whether there were pre-
ferred associations between dolphins observed handling octopus. There was evidence
of long-term preferred associations between dolphins handling octopus, however,
similar long-term preferred associations were also evident between dolphins with
octopus and dolphins never sighted predating on octopus. These initial findings are
not surprising given the strong social bonds that exist in this dolphin population.
Further information on the number of different dolphins that handle octopus is
needed to determine if octopus handling is indeed a socially learned behavior.
Off Bunbury, stomach content analyses of stranded dolphins (n=13) identified
squid beaks (n=6 of 10 that had prey parts), however octopus beaks were not
As the head of the octopuses were already removed during several of our
observations the heads may not have always been consumed, thus the beaks would
not be found in stomach contents. Therefore, the importance of octopus in the diet of
the Bunbury dolphin population remains unknown. However, octopuses, like other
cephalopods, are a source of high protein content and are common in the diet of
toothed whales (Clarke 1996, Santos et al. 2001a). From stomach content analysis,
Unpublished data, Shannon McCluskey, Ph.D. candidate, Murdoch University Cetacean Research
Unit, School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia.
benthic octopus are found in the diet of Tursiops the Spencer Gulf, Australia
(Gibbs et al. 2011), Brazil (dos Santos and Haimovici 2001), Hong Kong (Barros
et al. 2000), South Africa (Cockcroft and Ross 1990), Scotland (Santos et al. 2001b),
Ireland (Hernandez-Milian et al. 2015), and the Mediterranean Sea (Miokovic et al.
1999, Blanco et al. 2001, Pedaet al. 2015). Evolution of novel methods for process-
ing cephalopods could therefore have an important influence on the success of ceta-
cean species targeting these prey types.
This research complements the limited studies demonstrating that bottlenose dol-
phins carry out complex handling of prey. Octopus handling is a highly risky behav-
ior for bottlenose dolphins, especially if processing is not executed correctly. For an
animal to engage in such a risky behavior, the nutritional value of the prey must be
substantial. Hence, while octopus handling appears to be relatively rare in the popu-
lation, this prey and handling behavior might still be of great importance for dol-
phins, especially during periods when alternate prey may be limited.
Thank you to S. Leporati and F. Brice~no for discussions on octopus and assistance in species
identification. We thank our research assistants and S. McCluskey, M. Cannon, D. Chabanne,
V. Buchanan, and K. Nicholson, who participated with fieldwork and data processing. Thanks
to S. Allen, J. Symons, D. Harvey, and F. Harvey for off-survey effort octopus handling
records. We thank the partners of the South West Marine Research Program for financial sup-
port: Bemax Cable Sands, BHP Billiton Worsley Alumina Ltd, Bunbury Dolphin Discovery
Centre, Bunbury Port Authority, City of Bunbury, Cristal Mining, the Western Australian
Department of Parks and Wildlife, Iluka, Millard Marine, Naturaliste Charters, Newmont
Boddington Gold, South West Development Commission, and WA Plantation Resources. All
research was approved and permitted through the Department of Parks and Wildlife
(SF005811, SF007986, SF008624) and Murdoch University’s Animal Ethics Committee
(W2009/06, W2342/10). KS conceived the study. KS and HR carried out the field research
and analyses. LB conceived and obtained funding for the long-term research program. DH
assisted with video and photo analysis. KS wrote the paper with input from DH, LB, and HR.
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Received: 14 November 2016
Accepted: 8 February 2017
Supporting Information
The following supporting information is available for this article online at http://
Table S1. Survey effort pooled by austral season from March 2007 to August 2013,
including the number of on-effort sightings and average end group size (standard
Table S2. Summary of annual survey effort by transect location from March 2007
to August 2013.
Table S3. Mean dolphin group size (standard deviation) for each of the behavioral
Figure S1. Octopus tossing and shaking; row (a) an adult male dolphin tossing octo-
pus and leaping out of the water with the octopus still in its mouth, and row (b) an
adult female dolphin with a large shark bite on her left side (bottom left image) arch-
ing her body to shake octopus.
Movie S1. An octopus handling event by an adult male Indo-Pacific bottlenose dol-
phin off Bunbury, Western Australia, showing the different types of handling meth-
ods (shake and toss) used to process the octopus for easier consumption.
... The sample size was too small for any statistical comparisons between age class or sex of dolphins, however, we found that cephalopods made up an average of 45% of the proportion of female stomach contents, while cephalopods accounted for only an average of 2% of male stomach contents (Table 3). This finding is consistent with the dolphin behaviors observed by Sprogis et al. (2017a), who found that predominantly female dolphins tossed and shook octopus before consuming them in the inshore and coastal waters around Bunbury. Furthermore, mainly female dolphins were observed breaking cuttlefish apart before consuming them in the coastal waters of Bunbury during the cooler months (Smith and Sprogis, 2016). ...
... Based on the occurrence of octopus beaks in the stomachs of other populations of dolphins (Lagenorhynchus acutus in T. truncatus, T. aduncus) (Blanco et al., 2001;Gibbs et al., 2011;Hernandez-Milian et al., 2016), the relatively high protein value of cephalopods (Santos et al., 2001), and the observations of octopus and cuttlefish handling in the region (Smith and Sprogis, 2016;Sprogis et al., 2017a), octopus and cuttlefish were expected to be significant prey of dolphins in Bunbury. While squid beaks were identified in the dolphin stomachs (n ¼ 6 of 10 that had prey parts), no octopus or cuttlefish beaks were found. ...
... While squid beaks were identified in the dolphin stomachs (n ¼ 6 of 10 that had prey parts), no octopus or cuttlefish beaks were found. The whole heads of octopus have been observed to be consumed by dolphins off Bunbury (Stephens et al., 2017), and in other cases the head of octopus and cuttlefish is removed by tossing and shaking and may not be ingested, thus evading the retention of beaks by the dolphins (Smith and Sprogis, 2016;Sprogis et al., 2017a). Therefore, we cannot conclude that the lack of octopus and cuttlefish beaks detected in the limited number of dolphin stomachs from this study represented an absence of cephalopods from the Bunbury dolphins' diet. ...
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Insights into the food habits of predators are essential for maintaining healthy predator populations and the functioning of ecosystems. Stomach content and stable isotope analyses were used to investigate the foraging habits of an apex predator, the Indo-Pacific bottlenose dolphin (Tursiops aduncus) in south-western Australia. A total of 2,594 prey items from 26 families were identified from the stomachs of 10 deceased stranded dolphins. Fish otoliths from stomach contents were used to identify fish to family or species level. Ninety-three percent of identified stomach contents were perciforme fishes, however, perciformes comprised only 30% of the catch during prey sampling. Gobiidae species, small fish generally < 100 mm in total length, were the most prevalent family identified in dolphin stomachs, accounting for 82% of identified prey, yet Gobiidae accounted for 12.7% of the catch during prey sampling. For stable isotope analyses, tissue samples from 14 free-ranging dolphins were analyzed for nitrogen (δ¹⁵N) and carbon (δ¹³C) ratios. From stable isotope analyses and boat-based dolphin photo-identification surveys (n = 339, 2007-2011), results indicated niche differentiation between coastal and inshore (bay and estuarine habitat) dolphins. Carbon signatures showed that coastal dolphins had a more pelagic diet compared to a benthic diet observed in the inshore dolphins. Whereas, nitrogen signatures of coastal dolphins showed higher nitrogen levels than offshore dolphins, likely attributed to feeding on enriched prey typical of estuarian environments. Overall, these results indicated that bottlenose dolphins in the study area were selective foragers and that their foraging is specialized by the habitats most frequently used.
... This information is crucial because prey species and foraging behaviour may differ depending on age class and/or sex. Previous studies showed that females tend to forage during daytime more frequently than males (Barros & Wells, 1998;Sprogis et al., 2016Sprogis et al., , 2017. Moreover, the foraging dive duration of females varies in response to the age and sex of their calves such that females showed prolonged dive duration as their calves get older (Miketa et al., 2018). ...
... Bite (code B) is the state in which the dolphin bit and kept an organism in its beak but did not swallow (Barros & Wells, 1998). Organisms that corresponded to code B were referred to as potential prey species and represent cases where a dolphin bit and kept some organisms like fish in their mouths, playing and developing their foraging skills (Samarra et al., 2018), or when a dolphin tapped on the water surface and swung while biting an organism to make digestion easier (Smith & Sprogis, 2016;Sprogis et al., 2017). The observed prey species were identified using the features of their appearance in video footage. ...
... Such a female bias is consistent with previous studies of foraging behaviour in other areas, which reported that females tended to perform more daytime foraging behaviour than males in Sarasota Bay, Florida, in the United States (T. truncatus) and Bunbury, Western Australia, in Australia (T. aduncus) (Barros & Wells, 1998;Sprogis et al., 2016Sprogis et al., , 2017. ...
This study aimed to assess the prey species and foraging behaviour of Indo-Pacific bottlenose dolphins (Tursiops aduncus) around Mikura Island, a small oceanic island ~200 km south of Tokyo, Japan, using underwater observations and stomach content analysis of eight individuals to determine the feeding ecology of this population. Our results suggest that T. aduncus feed on various species and exhibit concentrated foraging behaviour at night. We recorded 11 fish species, seven cephalopod species, and one crustacean species as prey, as well as 10 fish species and one crustacean species as potential prey. Our underwater observations revealed that females performed foraging behaviour during daytime significantly more frequently than males. This is the first study using underwater observations to assess foraging and prey species of small cetaceans in Japan.
... Bottlenose dolphins exhibit diverse foraging behaviors (Shane 1990;Mann and Sargeant 2003) with the tactic employed determined by habitat features (e.g., Sargeant et al. 2007;Torres and Read 2009) or prey characteristics (Patterson and Mann 2011;Smith and Sprogis 2016;Sprogis et al. 2017). Prey selection is driven by maximizing net energy gain and depends on prey availability, abundance and distribution, inter-and intraspecific competition, and the consumer's ability to harvest resources (MacArthur and Pianka 1966;Bolnick 2001;Svanbäck and Bolnick 2007). ...
... Predominant behavior (i.e., > 50% of group members engaged [Mann 1999]) of foraging, travelling, socializing, resting, or unknown was recorded for the first 5 min and thereafter opportunistically. Previously described foraging tactics of peduncle dive foraging, bottom grubbing, snacking (Mann and Sargeant 2003;Sargeant et al. 2007), tossing (Sprogis et al. 2017), tail-whacking (Scott et al. 1990;Shane 1990), foraging along/against structures (described in this study), and begging (Finn et al. 2008;Senigaglia et al. 2019) were recorded (Table 1). Behavioral events (e.g., fish chases, handling, or capture of prey) were recorded opportunistically. ...
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Conspecifics may vary in their space use and diet leading to niche partitioning within populations. In social species, such partitioning may correspond to social structure as closely associated individuals likely encounter the same resources. This study investigated whether space use and diet varied among social clusters of a resident estuarine population of Indo-Pacific bottlenose dolphins. Dolphin photo-identification and behavioral data, as well as tissue samples for stable isotope analysis, were collected during boat-based surveys in the Peel-Harvey Estuary, Western Australia. Potential dolphin prey species were also collected for stable isotope analyses. Six mixing models, one assuming an invariant diet and others allowing for variation in diet according to sex, age class, and/or social cluster, were fitted to the data. The model with social cluster was the best fit and estimated detritivorous fish as the main dietary source for social clusters whose core activity space covered the eastern shores of the estuary and the rivers. These clusters occupied the lowest trophic position in the dolphin population. Benthic omnivores and carnivores contributed most to the diet of clusters whose core activity space included the two estuary entrances. These clusters occupied the highest trophic position. Clusters with core activity space located in the estuary basins reflected the overall mean contributions of fish feeding guilds to dolphin diet in this population. Detritivores, omnivores and herbivores, and benthic omnivores and carnivores each contributed approximately a third and water column species the remainder to the annual fish biomass removed from the estuary by the dolphin population. We conclude that dolphins share resources with fishers and piscivorous birds within the estuary. Significance statement This study identified intra-population resource partitioning according to social structure in a resident estuarine dolphin population. The heterogeneity in space use and diet among social clusters may result in individuals being susceptible to different pressures and threats. The dolphins’ foraging behavior and trophic interactions identified them as an apex predator in the Peel-Harvey Estuary, with their collective minimum annual food intake (~ 200,000 kg) exceeding the annual fish biomass removed by commercial fishers. As top predators in the system, dolphins may suppress prey populations through consumption and as agents of intimidation by changing prey distribution and behavior. This study provides scientific basis for recognizing dolphins as an important component of the Peel-Harvey Estuary ecosystem.
... There is a diversity of fishes in Exmouth Gulf that could represent potential dolphin prey, including trevally (Carangidae), emperor (Lutjanidae), snapper (Sparidae), and flathead (Platycephalidae) (Florisson et al. 2020). The full expanse of the diet of bottlenose dolphins in Exmouth Gulf remains unknown; however, it may be similar to the diet of Indo-Pacific bottlenose dolphins elsewhere in WA, which includes octopus (Sprogis et al. 2017), cuttlefish (Smith and Sprogis 2016), and a multitude of fish species (McCluskey et al. 2021;Nicholson et al. 2021). Humpback dolphins were not directly observed catching or chasing fish; therefore, it remains unknown as to what kind of prey they feed on in Exmouth Gulf. ...
Full-text available
Context. Exmouth Gulf is adjacent to the Ningaloo Marine Park, a UNESCO-listed area in Western Australia. The gulf remains largely unprotected, and is under increasing anthropogenic pressure from proposed industrial activities that pose threats to marine megafauna inhabiting the gulf. Threatened and near threatened species, such as the Australian humpback dolphin (Sousa sahulensis) and Indo-Pacific bottlenose dolphin (Tursiops aduncus), reside in the gulf; however, detailed information on their ecology and behaviour is lacking. Aims. The aim was to (1) provide baseline data on the distribution, encounter rate, group size and behaviour of coastal dolphins over an area where current industrial developments are proposed, and (2) report on the occurrence of other marine megafauna within this area. Methods. Boat-based photo-identification surveys were conducted on the western coastline of Exmouth Gulf along predetermined line transects (150 km 2) over austral autumn/winter 2021. Key results. Across 809.35 km of surveyed waters (181 h), a total of 93 bottlenose dolphin, 15 humpback dolphin, and six interspecific dolphin groups were sighted. Bottlenose dolphin groups were encountered at a rate of 0.077/km, humpback dolphin groups at 0.015/km and interspecific dolphin groups at 0.005/km. Dolphins were predominantly recorded in shallow (mean 10 m) and warm (mean 21°C) waters, and were commonly travelling and foraging. In total, 199 individual bottlenose dolphins and 48 humpback dolphins were photo-identified (excluding calves). There were 30 bottlenose dolphin calves (including three newborns) and four humpback dolphin calves (including two newborns) identified. Other marine megafauna group sightings included humpback whales (Megaptera novaeangliae; n = 32), southern right whales (Eubalaena australis, n = 1), dugongs (Dugong dugon, n = 25), turtles (n = 54), sea snakes (n = 27), manta rays (Mobula alfredi, n = 13) and sharks (n = 2). Conclusions. The presence of threatened marine species feeding, socialising, and resting highlights the importance of these waters for the identified species. Implications. The information provided is applicable for the spatial management and conservation efforts of these species, and aids in informing environmental impact assessments of individual and cumulative pressures.
... For instance, mixed species groups of humpback and bottlenose dolphin groups have been recorded at the North West Cape, where offshore and inshore waters are channelled and mixed (Brown et al., 2012;Hunt et al., 2017). This is plausible as both species are "opportunistic-generalist feeders, " consuming a wide range of benthic and pelagic fish and cephalopod species (Amir et al., 2005;Parra and Jedensjö, 2014;McCluskey et al., 2016;Smith and Sprogis, 2016;Sprogis et al., 2017b). As there are many unresolved questions, targeted observational studies are required to understand foraging strategies and the mechanisms underlying mixed species group formation and behaviour (Syme et al., 2021). ...
Full-text available
Understanding species’ distribution patterns and the environmental and ecological interactions that drive them is fundamental for biodiversity conservation. Data deficiency exists in areas that are difficult to access, or where resources are limited. We use a broad-scale, non-targeted dataset to describe dolphin distribution and habitat suitability in remote north Western Australia, where there is a paucity of data to adequately inform species management. From 1,169 opportunistic dolphin sightings obtained from 10 dugong aerial surveys conducted over a four-year period, there were 661 Indo-Pacific bottlenose dolphin ( Tursiops aduncus ), 191 Australian humpback dolphin ( Sousa sahulensis ), nine Australian snubfin dolphin ( Orcaella heinsohni ), 16 Stenella sp., one killer whale ( Orcinus orca ), one false killer whale ( Pseudorca crassidens ), and 290 unidentified dolphin species sightings. Maximum Entropy (MaxEnt) habitat suitability models identified shallow intertidal areas around mainland coast, islands and shoals as important areas for humpback dolphins. In contrast, bottlenose dolphins are more likely to occur further offshore and at greater depths, suggesting niche partitioning between these two sympatric species. Bottlenose dolphin response to sea surface temperature is markedly different between seasons (positive in May; negative in October) and probably influenced by the Leeuwin Current, a prominent oceanographic feature. Our findings support broad marine spatial planning, impact assessment and the design of future surveys, which would benefit from the collection of high-resolution digital images for species identification verification. A substantial proportion of data were removed due to uncertainties resulting from non-targeted observations and this is likely to have reduced model performance. We highlight the importance of considering climatic and seasonal fluctuations in interpreting distribution patterns and species interactions in assuming habitat suitability.
... Throws are oriented towards the direction of the prey (9), though the throws may function as much to destabilize the walls of the trap as to disrupt behavior of the prey itself. The processing of prey by various predators, such as dolphins, also features thrashing and tossing (10). ...
Wild octopuses at an Australian site frequently propel shells, silt, and algae through the water by releasing these materials from their arms while creating a forceful jet from the siphon held under the arm web. These "throws" occur in several contexts, including interactions with conspecifics, and material thrown in conspecific contexts frequently hits other octopuses. Some throws appear to be targeted on other individuals and play a social role, as suggested by several kinds of evidence. Such throws were significantly more vigorous and more often used silt, rather than shells or algae, and high vigor throws were significantly more often accompanied by uniform or dark body patterns. Some throws were directed differently from beneath the arms and such throws were significantly more likely to hit other octopuses. Throws targeted at other individuals in the same population, as these appear to be, are the least common form of nonhuman throwing.
... The method is used by the killer whale and leopard seal among marine mammals , and crocodiles among reptiles (Ng and Mendyk, 2012;Pooley and Gans, 1976). Bottlenose dolphins are also known to use similar behaviors to tear prey (Sprogis et al., 2017), although they are not megapredators. None of these predators use cutting teeth when tearing the prey, i.e., the leopard seal uses the canine and peg-like incisors but not the carnassial, whereas others lack cutting teeth. ...
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Air-breathing marine predators have been essential components of the marine ecosystem since the Triassic. Many of them are considered the apex predators but without direct evidence—dietary inferences are usually based on circumstantial evidence, such as tooth shape. Here we report a fossil that likely represents the oldest evidence for predation on megafauna, i.e., animals equal to or larger than humans, by marine tetrapods—a thalattosaur (∼4 m in total length) in the stomach of a Middle Triassic ichthyosaur (∼5 m). The predator has grasping teeth yet swallowed the body trunk of the prey in one to several pieces. There were many more Mesozoic marine reptiles with similar grasping teeth, so megafaunal predation was likely more widespread than presently conceived. Megafaunal predation probably started nearly simultaneously in multiple lineages of marine reptiles in the Illyrian (about 242–243 million years ago).
... Dolphins visit the dedicated foodprovisioning area mainly during summer months (November to March), which correspond to the peak calving season (Smith, Frère, Kobryn, & Bejder, 2016). This resident dolphin population has been extensively studied and information is available on the population's abundance, sociality, habitat use, foraging ecology and genetic connectivity (McCluskey et al. 2016;Smith et al. 2016;Sprogis et al. 2017;Manlik et al. 2019). Dolphin's abundance varies seasonally between 76 to 185 (excluding calves) (Kate R. Sprogis, Pollock, et al., 2016) and population viability analyses forecasts the population to decline at current levels of reproduction and mortality . ...
Marine wildlife tourism attractions often use food rewards to ensure close-up encounters withfree-ranging animals. In Bunbury, Western Australia, the Dolphin Discovery Centre (DDC) conductsa food-provision program where bottlenose dolphins (N= 22; between 2000-2018) are offered foodrewards to encourage their visitation at a beach in front of the DDC. We used historical records onindividual beach visits by adult female dolphins collected by the DDC from 2000 to 2018 to developgeneralized mixed effects models (GLMM) to test whether the frequency of beach visitation wasinfluenced by their reproductive status (pregnant, lactating, non-reproductive) or climatic events (ElNiño-Southern Oscillation phases) that could affect prey availability. We also quantified thebehavioural budget of dolphins during food-provisioning sessions and documented intra and interspecificaggressive behaviours using individual focal follows collected in 2017-2018. Provisionedfemales spend most of the time resting within the interaction area (66.3%) and aggressive interactionsarise as a consequence of dominance behaviour over food access. Visitation rates were mostinfluenced by reproductive status with pregnant and lactating females visiting more frequently theprovisioning area (z = 2.085; p = 0.037 and z = 2.437; p = 0.014, respectively). Females thatfrequently visit the provisioning area expose their dependent calves to regular human interactions atan early age when they are more susceptible to behavioural conditioning. Such experiences couldcause the loss of awareness towards humans and promote maladaptive behaviours such as begging,that increase risk of entanglement in fishing gear, boat strikes and propeller injuries.
... Indeed, our habitat and geomorphic data may only be indirectly related to important determining factors, although Torres et al. (2008) found that for inshore areas use of habitat characteristics yielded better results than using direct measures of prey abundance. Bottlenose dolphins have a very complex social structure, so their distributions could be influenced not only by prey availability (Hartel, 2010;McCluskey et al., 2016;Zanardo et al., 2017) but also by group dynamics (Lois et al., 2018;Sprogis et al., 2018), predator avoidance (Heithaus and Dill, 2002;Heithaus and Dill, 2006), competition (Lois et al., 2018), foraging specialization (Sprogis et al., 2017), and even human disturbance (Bossley et al., 2016); and these variables should be considered in greater detail in future analysis of the population. In this context, our observations on group size versus possible predation threat and of social behavior related to inshore distribution represent only a first approach into understanding these additional drivers. ...
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Pinnipeds generally target relatively small prey that can be swallowed whole, yet often include larger prey in their diet. To eat large prey, they must first process it into pieces small enough to swallow. In this study we explored the range of prey-processing behaviors used by Australian sea lions (Neophoca cinerea) when presented with large prey during captive feeding trials. The most common methods were chewing using the teeth, shaking prey at the surface, and tearing prey held between the teeth and forelimbs. Although pinnipeds do not masticate their food, we found that sea lions used chewing to create weak points in large prey to aid further processing and to prepare secured pieces of prey for swallowing. Shake feeding matches the processing behaviors observed in fur seals, but use of forelimbs for " hold and tear " feeding has not been previously reported for other otariids. When performing this processing method, prey was torn by being stretched between the teeth and fore-limbs, where it was secured by being squeezed between the palms of their flippers. These results show that Australian sea lions use a broad repertoire of behaviors for prey processing, which matches the wide range of prey species in their diet.
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Prey density has long been associated with prey profitability for a predator, but prey quality has seldom been quantified. We assessed the potential prey availability and calorific value for Indo-Pacific bottlenose dolphins (Tursiops aduncus) in an estuarine and coastal environment of temperate south-western Australia. Fish were sampled using three methods across three regions (Estuary, Bay and Ocean) in the study area using a 21.5 m beach seine, multi-mesh gillnet, and fish traps. The total biomass and numbers of all species and those of potential dolphin prey were determined in austral summers and winters between 2007 and 2010. The calorific value of 19 species was determined by bomb calorimetry. The aim of the research was to evaluate the significance of prey availability in explaining the higher abundance of dolphins in the region in summer versus winter across years. A higher abundance of prey was captured in the summer (mean of two summer seasons ± 1 SE = 12,080 ± 160) than in the winter (mean of two winter seasons = 7,358 ± 343) using the same number of gear sets in each season and year. In contrast, a higher biomass of potential dolphin prey, of higher energy content, were captured during winters than summers, when fewer dolphins are present in the area. Variability was significant between season and region for the gillnet (p < 0.01), and seine (p < 0.01). The interaction of season and region was also significant for the calorific content captured by the traps (p < 0.03), and between the seasons for biomass of the trap catch (p < 0.02). The dolphin mother and calf pairs that remain in the Estuary and Bay year round may be sustained by the higher quality, and generally larger, if lesser abundant, prey in the winter months. Furthermore, factors such as predator avoidance and mating opportunities are likely to influence patterns of local dolphin abundance. This study provides insights into the complex dynamics of predator – prey interactions, and highlights the importance for a better understanding of prey abundance, distribution and calorific content in explaining the spatial ecology of large apex predators.
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We report on observations of Indo-Pacific bottlenose dolphins (Tursiops aduncus) feeding on giant cuttlefish (Sepia apama) from March 2007 to April 2013 in the temperate waters off Bunbury, south-western Australia. Seventeen feeding events were observed during the cooler months between July and September in relatively shallow coastal waters, with 12 dolphins identified as adult females. We observed behavioural sequences of complex prey-handling of cuttlefish where dolphins’ used multiple steps to remove the cuttlefish head, ink and cuttlebone before consuming the flesh of the cuttlefish mantle. Our study provides valuable information to the limited knowledge on the complex prey-handling by T. aduncus on cuttlefish in Australia, and is complementary to other known specialised foraging behaviours of bottlenose dolphins. This study also details a different behavioural sequence of cuttlefish prey-handling to that of the bottlenose dolphins in the Sado estuary, Portugal, where only the head is consumed, and to the Spencer Gulf, Australia, in that the dolphins in Bunbury carry the cuttlefish mantle over their rostrum before removing the cuttlebone. Information on S. apama in Bunbury is scarce, therefore studies on abundance, distribution and egg-laying sites are recommended in order to enable informed decision making and to understand the importance of S. apama to the diet of T. aduncus.
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Conservation management typically focuses on protecting wildlife habitat that is linked to important behaviours such as resting, breeding or caring for young. However, development of conservation strategies of social species would benefit from inclusion of social dynamics, particularly for species where social relationships influence fitness measures such as survival and reproduction. We combined the study of dolphin sociality, distribution and calving to identify important behavioural and ecological patterns to inform management. Over 3 consecutive years, 231 boat-based photo-identification surveys were conducted to individually identify adult female bottlenose dolphins over a 120 km2 area in Bunbury, Western Australia. The density distribution of female dolphins was highest in the inner waters during December–February (austral summer) and March (early autumn), which also coincided in time with the majority of calving. The temporal stability of social bonds between adult females was measured (using lagged association rates) and remained stable over multiple years. A cyclic model best described female–female associations with an annual peak occurring each austral summer (Dec–Jan–Feb). These results informed the implementation of a legislative no-go area and vessel speed restriction areas. In addition to conventional management approaches of protecting important habitat and breeding periods, our measure of dolphin sociality provides a new metric to consider in conservation efforts. We encourage studies on socially complex species to incorporate social dynamics when evaluating possible impacts of anthropogenic activities.
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Inherent difficulties in determining the sex of free-ranging sexually monomorphic species often prevents a sex-specific focus on estimating abundance, movement patterns and survival rates. This study provides insights into sex-specific population parameters of Indo-Pacific bottlenose dolphins (Tursiops aduncus). Systematic, boat-based photoidentification surveys (n = 417) were conducted year-round from 2007 to 2013 in coastal and estuarine waters off Bunbury, Western Australia. Pollock’s Robust Design was used to quantify population parameters for three datasets: (i) adults and juveniles combined, (ii) adult females and, (iii) adult males. For all datasets, abundance estimates varied seasonally, with general highs during summer and/or autumn, and lows during winter. Dolphins had seasonally structured temporary emigration rates with similar trends between sexes. The derived return rate (1-γ’) of temporary emigrants into the study area was highest from winter to spring, indicating that dolphins had a high probability of return into the study area during spring. We suggest that the return of dolphins into the study area and increase in abundance is influenced by the breeding season (summer/autumn). Prey availability is likely a main driver responsible for the movement of dolphins out of the study area during winter. Seasonal apparent survival rates were constant and high (0.98–0.99) for all datasets. High apparent survival rates suggest there is no permanent emigration from the study area. Our sex-specific modeling approach offers a comprehensive interpretation of the population dynamics of a top predator in a coastal and estuarine environment and acts as a model for future sex-based population studies on sexually monomorphic species.
The Australasian region is home to the greatest diversity of cephalopods — squid, cuttlefish, octopuses — in the world. Yet, we know very little about these fascinating marine animals. This book provides insights into the biology and behaviour of more than 60 species. From the Giant Squid to the deadly Blue-ringed Octopus, the secret lives of cephalopods are revealed in a highly readable form with outstanding colour images and informative text. For each species there is a distribution map and identification notes which summarise the main features to look for. While the book focuses on species found in relatively shallow coastal waters, a few of the more bizarre deeper-water species are included. Naturalists, divers, reef-walkers and anglers will find the book authoritative, yet very easy to use. A comprehensive section illustrating cuttlebones will enable beachcombers to identify most of the species they are likely to encounter.
This paper presents data on the prey of one bottlenose dolphin (Tursiops truncatus) in the Adriatic Sea and a comparison with other findings about the feeding of this species in the Mediterranean. The stomach contents of this bottlenose dolphin caught in a fishing net in the area near the town of Sibenik in December 1995 were examined. In the prey we identified 3 species of fish (conger eel, Conger conger; hake, Merluccius merluccius and pandora, Pagellus erythrinus) and one cephalopod species (squid, Loligo vulgaris). It was found that these data are consistent with other data relating to dolphin feeding.