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SF Journal of Biotechnology and Biomedical Engineering
2018 | Volume 1 | Edition 2 | Article 1007
ScienceForecast Publications LLC., | https://scienceforecastoa.com/ 1
1
The Sea Stars (Echinodermata: Asteroidea): Their Biology,
Ecology, Evolution and Utilization
OPEN ACCESS
*Correspondence:
Rahman MA, World Fisheries University
Pilot Programme, Pukyong National
University (PKNU), 45 Yongso-ro, Nam-
gu, Busan 48513, Korea.
E-mail: aminur1963@gmail.com;
aminur2017@pknu.ac.kr
Received Date: 27 Jul 2018
Accepted Date: 10 Sep 2018
Published Date: 17 Sep 2018
Citation: Rahman MA, Molla MHR,
Megwalu FO, Asare OE, Tchoundi
A, Shaikh MM, et al. The Sea Stars
(Echinodermata: Asteroidea): Their
Biology, Ecology, Evolution and
Utilization. SF J Biotechnol Biomed
Eng. 2018; 1(2): 1007.
Copyright © 2018 Rahman MA. This is
an open access article distributed under
the Creative Commons Attribution
License, which permits unrestricted
use, distribution, and reproduction in
any medium, provided the original work
is properly cited.
Review Article
Published: 17 Sep, 2018
Abstract
e Sea stars (Asteroidea: Echinodermata) are comprising of a large and diverse groups of sessile
marine invertebrates having seven extant orders such as Brisingida, Forcipulatida, Notomyotida,
Paxillosida, Spinulosida, Valvatida and Velatida and two extinct one such as Calliasterellidae and
Trichasteropsida. Around 1,500 living species of starsh occur on the seabed in all the world's oceans,
from the tropics to subzero polar waters. ey are found from the intertidal zone down to abyssal
depths, 6,000m below the surface. Starsh typically have a central disc and ve arms, though some
species have a larger number of arms. e aboral or upper surface may be smooth, granular or spiny,
and is covered with overlapping plates. Many species are brightly colored in various shades of red or
orange, while others are blue, grey or brown. Starsh have tube feet operated by a hydraulic system
and a mouth at the center of the oral or lower surface. ey are opportunistic feeders and are mostly
predators on benthic invertebrates. ey have complex life cycles and can reproduce both sexually
and asexually. Most can regenerate damaged parts or lost arms and they can shed arms as a means
of defense. e Asteroidea occupy several signicant ecological roles. Starsh, such as the ochre sea
star (Pisaster ochraceus) and the reef sea star (Stichaster australis), have become widely known as
examples of the keystone species concept in ecology. ey are sometimes collected as curios, used in
design or as logos, and in some cultures, despite possible toxicity, they are eaten. Starsh have been
the recent research topic due to their diverse bioactivities, excellent pharmacological properties and
complex secondary metabolites including steroids, steroidal glycosides, anthraquinones, alkaloids,
phospholipids, peptides, and fatty acids. ese chemical constituents exhibit cytotoxic, hemolytic,
antiviral, antifungal, and antimicrobial activities and thus have important implications for human
health benets.
Keywords: Starsh; Biology; Ecology; Evolution; Bioactive compounds
Rahman MA1*, Molla MHR1, Megwalu FO1, Asare OE1, Tchoundi A1, Shaikh MM1 and Jahan B2
1World Fisheries University Pilot Programme, Pukyong National University (PKNU), Nam-gu, Busan, Korea
2Biotechnology and Genetic Engineering Discipline, Khulna University, Khulna, Bangladesh
Introduction
Echinoderms are an entirely marine phylum whose populations are prevalent in benthic
ecosystems throughout the world's oceans. Starsh or sea stars are echinoderms belonging to
the class Asteroidea. ey are a large and diverse class having seven extant orders viz. Brisingida,
Forcipulatida, Notomyotida, Paxillosida, Spinulosida, Valvatida and Velatida and two extint
one such as Calliasterellidae and Trichasteropsida [1,2]. Approximately 1,500 living species of
starsh occur on the seabed in all the world's oceans, from the tropics to subzero polar waters. e
scientic name Asteroidea was given to starsh by the French zoologist de Blainville in 1830. It is
derived from a star and form, likeness, appearance [3]. e class Asteroidea belongs to the phylum
Echinodermata. As well as the starsh, the echinoderms include sea urchins, sand dollars, brittle
and basket stars, sea cucumbers and crinoids.
e larvae of echinoderms have bilateral symmetry, but during metamorphosis, this is replaced
with radial symmetry, typically pentameric [4]. Adult echinoderms are characterized by having a
water vascular system with external tube feet and a calcareous endoskeleton consisting of ossicles
connected by a mesh of collagen bres [5]. Starsh are included in the subphylum Asterozoa, the
characteristics of which include a attened, star-shaped body as adults consisting of a central disc
and multiple radiating arms. e subphylum includes the two classes of Asteroidea, the starsh,
and Ophiuroidea, the brittle stars and basket stars. Asteroids have broad-based arms with skeletal
support provided by calcareous plates in the body wall, while ophiuroids have clearly demarcated
slender arms strengthened by paired fused ossicles forming jointed vertebrate [6].
Most starsh have ve arms that radiate from a central disc, but the number varies with the
Rahman MA, et al., SF Journal of Biotechnology and Biomedical Engineering
2018 | Volume 1 | Edition 2 | Article 1007
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group. It is not unusual in species that typically have ve arms
for some individuals to possess six or more through abnormal
development [7].
Starsh Biology
e body wall consists of a thin cuticle, an epidermis consisting
of a single layer of cells, a thick dermis formed of connective
tissue and a thin coelomic myoepithelial layer, which provides the
longitudinal and circular musculature. e dermis contains an
endoskeleton of calcium carbonate components known as ossicles.
ese are honeycombed structures composed of calcite microcrystals
arranged in a lattice [8]. ey vary in form, with some bearing
external granules, tubercles and spines, but most are tabular plates
that t neatly together in a tessellated manner and form the main
covering of the aboral surface [9]. Some are specialized structures
such as the madreporite (the entrance to the water vascular system),
pedicellariae and paxillae [10]. Pedicellariae are compound ossicles
with forceps-like jaws. ey remove debris from the body surface and
wave around on exible stalks in response to physical or chemical
stimuli while continually making biting movements. ey oen
form clusters surrounding spines [9,10]. Several groups of starsh,
including Valvatida and Forcipulatida, possess pedicellariae [11]. In
Forcipulatida, such as Asterias and Pisaster, they occur in pompom-
like tus at the base of each spine, whereas in the Goniasteridae,
such as Hippasteria phrygiana, the pedicellariae are scattered over
the body surface. Some are thought to assist in defence, while others
aid in feeding or in the removal of organisms attempting to settle on
the starsh's surface [12]. Some species like Novodinia antillensis and
Labidiaster annulatus use their large pedicellariae to capture small
sh and crustaceans [13].
ere may also be papulae, thin-walled protrusions of the
body cavity that reach through the body wall and extend into the
surrounding water. e structures are supported by collagen bres
set at right angles to each other and arranged in a three-dimensional
web with the ossicles and papulae in the interstices. is arrangement
enables both easy exion of the arms by the starsh and the rapid
onset of stiness and rigidity required for actions performed under
stress [14].
Water vascular system
e water vascular system of the starsh is a hydraulic system
made up of a network of uid-lled canals and is concerned with
locomotion, adhesion, food manipulation and gas exchange.
Water enters the system through the madreporite, a porous, oen
conspicuous, sieve-like ossicle on the aboral surface. It is linked
through a stone canal, oen lined with calcareous material, to a ring
canal around the mouth opening. ere are usually two rows of tube
feet but in some species, the lateral canals are alternately long and
short and there appearing to be four rows. e interior of the whole
canal system is lined with cilia [15].
When longitudinal muscles in the ampullae contract, valves in
the lateral canals close and water is forced into the tube feet. ese
extend to contact the substrate. Although the tube feet resemble
suction cups in appearance, the gripping action is a function of
adhesive chemicals rather than suction [16]. Other chemicals and
relaxation of the ampullae allow for release from the substrate. Most
starsh cannot move quickly, a typical speed being that of the leather
star (Dermasterias imbricata), which can manage just 15 cm in a
minute [17]. Some burrowing species from the genera Astropecten
and Luidia have points rather than suckers on their long tube feet and
are capable of much more rapid motion, "gliding" across the ocean
oor. e sand star (Luidia foliolata) can travel at a speed of 2.8 m
per minute [18].
Gas exchange also takes place through other gills known as
papulae, which are thin-walled bulges on the aboral surface of the
disc and arms. Oxygen is transferred from these to the coelomic uid,
which acts as the transport medium for gasses. Oxygen dissolved in
the water is distributed through the body mainly by the uid in the
main body cavity; the circulatory system may also play a minor role
[19].
Digestive system and excretion
e gut of a starsh occupies most of the disc and extends into the
arms. e cardiac stomach is glandular and pouched and is supported
by ligaments attached to ossicles in the arms so it can be pulled back
into position aer it has been everted. e pyloric stomach has two
extensions into each arm: the pyloric caeca. ese are elongated,
branched hollow tubes that are lined by a series of glands, which
secrete digestive enzymes and absorb nutrients from the food. A short
intestine and rectum run from the pyloric stomach to open at a small
anus at the apex of the aboral surface of the disc [20]. e semi-digested
uid is passed into their pyloric stomachs and caeca where digestion
continues and absorption ensues [21]. In more advanced species of
starsh, the cardiac stomach can be everted from the organism's body
to engulf and digest food. When the prey is a clam or other bivalve,
the starsh pulls with its tube feet to separate the two valves slightly,
and inserts a small section of its stomach, which releases enzymes
to digest the prey. e stomach and the partially digested prey are
later retracted into the disc. Here the food is passed on to the pyloric
stomach, which always remains inside the disc [22]. e retraction
and contraction of the cardiac stomach is activated by a neuropeptide
known as NGFFYamide [22]. Some starsh are not pure carnivores,
supplementing their diets with algae or organic detritus. Some of
these species are grazers, but others trap food particles from the water
in sticky mucus strands that are swept towards the mouth along
ciliated grooves [21]. ese cells engulf waste material, and eventually
migrate to the tips of the papulae, where a portion of body wall is
nipped o and ejected into the surrounding water. Some waste may
also be excreted by the pyloric glands and voided with the faces [20].
Starsh do not appear to have any mechanisms for osmoregulation,
and keep their body uids at the same salt concentration as the
surrounding water. Although some species can tolerate relatively
low salinity, the lack of an osmoregulation system probably explains
why starsh are not found in fresh water or even in many estuarine
environments [20].
Sensory and nervous systems
Although starsh do not have many well-dened sense organs,
they are sensitive to touch, light, temperature, orientation and the
status of the water around them. e tube feet, spines and pedicellariae
are sensitive to touch. e tube feet, especially those at the tips of the
rays, are also sensitive to chemicals, enabling the starsh to detect
odour sources such as food [21]. Many starsh also possess individual
photoreceptor cells in other parts of their bodies and respond to light
even when their eyespots are covered. Whether they advance or
retreat depends on the species [23]. While a starsh lacks a centralized
brain, it has a complex nervous system with a nerve ring around the
mouth and a radial nerve running along the ambulacral region of
each arm parallel to the radial canal. e peripheral nerve system
Rahman MA, et al., SF Journal of Biotechnology and Biomedical Engineering
2018 | Volume 1 | Edition 2 | Article 1007
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consists of two nerve nets: a sensory system in the epidermis and a
motor system in the lining of the coelomic cavity. Neurons passing
through the dermis connect the two [23]. e starsh does not have
the capacity to plan its actions. If one arm detects an attractive odour,
it becomes dominant and temporarily over-rides the other arms to
initiate movement towards the prey. e mechanism for this is not
fully understood [23].
Circulatory system
e body cavity contains the circulatory or haemal system. e
vessels form three rings: one around the mouth (the hyponeural
haemal ring), another around the digestive system (the gastric ring)
and the third near the aboral surface (the genital ring). e heart beats
about six times a minute and is at the apex of a vertical channel (the
axial vessel) that connects the three rings. At the base of each arm
are paired gonads; a lateral vessel extends from the genital ring past
the gonads to the tip of the arm. is vessel has a blind end and there
is no continuous circulation of the uid within it. is liquid does
not contain a pigment and has little or no respiratory function but is
probably used to transport nutrients around the body [24].
Secondary metabolites
Starsh produce a large number of secondary metabolites in the
form of lipids, including steroidal derivatives of cholesterol, and fatty
acid amides of sphingosine. e steroids are mostly saponins, known
as asterosaponins, and their sulphated derivatives. ey vary between
species and are typically formed from up to six sugar molecules
(usually glucose and galactose) connected by up to three glycosidic
chains. Long-chain fatty acid amides of sphingosine occur frequently
and some of them have known pharmacological activity. Some are
feeding deterrents used by the starsh to discourage predation.
Others are antifoulants and supplement the pedicellariae to prevent
other organisms from settling on the starsh's aboral surface. Some
are alarm pheromones and escape-eliciting chemicals, the release
of which trigger responses in conspecic starsh but oen produce
escape responses in potential prey [25]. Research into the ecacy
of these compounds for possible pharmacological or industrial use
occurs worldwide [26].
Sexual reproduction
Most species of starsh are gonochorous, there being separate
male and female individuals. Some species are simultaneous
hermaphrodites, producing eggs and sperm at the same time and in a
few of these, the same gonad, called an ovotestis, produces both eggs
and sperm [27]. When these grow large enough they change back into
females [28]. In others, the eggs may be stuck to the undersides of rocks
[29]. In certain species of starsh, the females brood their eggs – either
by simply enveloping them [29] or by holding them in specialized
structures. Brooding may be done in pockets on the starsh's aboral
surface, [30-31] inside the pyloric stomach (Leptasterias tenera) [32]
or even in the interior of the gonads themselves [27]. ose starsh
that brood their eggs by "sitting" on them usually assume a humped
posture with their discs raised o the substrate [33]. Pteraster militaris
broods a few of its young and disperses the remaining eggs, that are
too numerous to t into its pouch [29]. In these brooding species, the
eggs are relatively large, and supplied with yolk, and they generally
develop directly into miniature starsh without an intervening
larval stage [27]. An intragonadal brooder, the young starsh obtain
nutrients by eating other eggs and embryos in the brood pouch [34].
Brooding is especially common in polar and deep-sea species that
live in environments unfavorable for larval development [36] and in
smaller species that produce just a few eggs [40-41].
Spawning takes place at any time of year, each species having
its own characteristic breeding season [37]. e rst individual of a
species to spawn may release a pheromone that serves to attract other
starsh to aggregate and to release their gametes synchronously [38].
In other species, a male and female may come together and form a pair
[39-40]. is behavior is called pseudocopulation [41] and the male
climbs on top, placing his arms between those of the female. When
she releases eggs into the water, he is induced to spawn [38]. Starsh
may use environmental signals to coordinate the time of spawning
(day length to indicate the correct time of the year, [39] dawn or dusk
to indicate the correct time of day), and chemical signals to indicate
their readiness to breed. In some species, mature females produce
chemicals to attract sperm in the sea water [42].
Asexual reproduction
Some species of starsh are able to reproduce asexually as adults
either by ssion of their central discs [48] or by autonomy of one or
more of their arms. Which of these processes occurs depends on the
genus. Among starsh that are able to regenerate their whole body
from a single arm, some can do so even from fragments just 1 cm
(0.4 in) long [49]. Single arms that regenerate a whole individual are
called comet forms. e division of the starsh, either across its disc
or at the base of the arm, is usually accompanied by a weakness in the
structure that provides a fracture zone [50].
e larvae of several species of starsh can reproduce asexually
before they reach maturity [51]. ey do this by autotomizing some
parts of their bodies or by budding [52]. When such a larva senses
that food is plentiful, it takes the path of asexual reproduction rather
than normal development [53]. ough this costs it time and energy
and delays maturity, it allows a single larva to give rise to multiple
adults when the conditions are appropriate [52].
Some species of starsh have the ability to regenerate lost arms
and can regrow an entire new limb given time [49]. A few can regrow
a complete new disc from a single arm, while others need at least part
of the central disc to be attached to the detached part [24]. Regrowth
can take several months or years [49] and starsh are vulnerable to
infections during the early stages aer the loss of an arm. A separated
limb lives o stored nutrients until it regrows a disc and mouth, and
is able to feed again [49]. Other than fragmentation carried out for
the purpose of reproduction, the division of the body may happen
inadvertently due to part being detached by a predator, or part may
be actively shed by the starsh in an escape response [24]. e loss of
parts of the body is achieved by the rapid soening of a special type of
connective tissue in response to nervous signals. is type of tissue is
called catch connective tissue and is found in most echinoderms [54].
An autonomy-promoting factor has been identied which, when
injected into another starsh, causes rapid shedding of arms [55].
Larval development and maturation
Most starsh embryos hatch at the blastula stage. e original
ball of cells develops a lateral pouch, the archenteron. e entrance
to this is known as the blastopore and it will later develop into the
anus. Another invagination of the surface will fuse with the tip of
the archenteron as the mouth while the interior section will become
the gut. At the same time, a band of cilia develops on the exterior.
is enlarges and extends around the surface and eventually onto
two developing arm-like outgrowths. At this stage the larva is known
as a bipinnaria. e cilia are used for locomotion and feeding, their
Rahman MA, et al., SF Journal of Biotechnology and Biomedical Engineering
2018 | Volume 1 | Edition 2 | Article 1007
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rhythmic beat waing phytoplankton towards the mouth [8].
e lifecycle of a starsh varies considerably between species,
generally being longer in larger forms and in those with planktonic
larvae. For example, Leptasterias bexactis broods a small number
of large-yolked eggs. It has an adult weight of 20g, reaches sexual
maturity in two years and lives for about ten years [8]. Pisaster
ochraceus releases a large number of eggs into the sea each year and
has an adult weight of 80g. It reaches maturity in ve years and has a
maximum recorded lifespan of 34 years [8].
Starsh Ecology
Distribution and habitat
Echinoderms, including starsh, maintain a delicate internal
electrolyte balance that is in equilibrium with seawater. is means
that it is only possible for them to live in a marine environment and
they are not found in any freshwater habitats. Starsh species inhabit
all of the world's oceans. Habitats range from tropical coral reefs,
rocky shores, tidal pools, mud, and sand to kelp forests, sea grass and
the deep-sea oor down to at least 6,000m [51]. e greatest diversity
of species occurs in coastal areas, some of which are shown in Figure
1.
Diet preference
Most species of starsh are generalist predators, eating
microalgae, sponges, bivalves, snails and other small animals [52].
e crown-of-thorns starsh consumes coral polyps, [53] while other
species are detritivores, feeding on decomposing organic material
and faecal matter [52,54]. A few are suspension feeders, gathering in
phytoplankton; Henricia and Enhinaster oen occur in association
with sponges, beneting from the water current they produce [55].
Various species have been shown to be able to absorb organic
nutrients from the surrounding water, and this may form a signicant
portion of their diet [55]. e processes of feeding and capture may be
aided by special parts; Pisaster brevispinus, the short-spined pisaster
from the West Coast of America, can use a set of specialized tube feet
to dig itself deep into the so substrate to extract prey [56].
Ecological impact
Starsh are keystone species in their respective marine
communities. eir relatively large sizes, diverse diets and ability to
adapt to dierent environments makes them ecologically important
[57]. Experimental removals of this top predator from a stretch
of shoreline resulted in lower species diversity and the eventual
domination of Mytilus mussels, which were able to outcompete
other organisms for space and resources [58]. Similar results were
found in a 1971 study of Stichasrter australis on the intertidal coast
of the South Island of New Zealand. S. australis was found to have
removed most of a batch of transplanted mussels within two or three
months of their placement, while in an area from which S. australis
had been removed, the mussels increased in number dramatically,
overwhelming the area and threatening biodiversity [59]. e feeding
activity of the omnivorous starsh Oreaster reticulatus on sandy and
seagrass bottoms in the Virgin Islands appears to regulate the diversity,
distribution and abundance of microorganisms. ese starsh engulf
piles of sediment removing the surface lms and algae adhering to
the particles [60]. In addition, foraging by these migratory starsh
creates diverse patches of organic matter, which may play a role in
the distribution and abundance of organisms such as sh, crabs and
sea urchins that feed on the sediment [61]. Starsh sometimes have
negative eects on ecosystems. Outbreaks of crown-of-thorns starsh
have caused damage to coral reefs in Northeast Australia and French
Polynesia [62]. e species has since grown in numbers to the point
where they threaten commercially important bivalve populations.
As such, they are considered pests, and are on the Invasive Species
Specialist Group's list of the world's 100 worst invasive species [63].
Threats
Starsh may be preyed on by conspecics, other starsh
species, tritons, crabs, sh, gulls and sea otters [64,65]. eir rst
lines of defense are the saponins present in their body walls, which
have unpleasant avours [66]. Several species sometimes suer
from a wasting condition caused by bacteria in the genus Vibrio;
[64] however, a more widespread wasting disease, causing mass
mortalities among starsh, appears sporadically. A paper published
in November 2014 revealed the most likely cause of this disease to
be a densovirus the authors named sea star-associated densovirus
(SSaDV) [67]. e protozoan Orchitophrya stellarum is known to
infect the gonads of starsh and damage tissue [64]. Starsh are
vulnerable to high temperatures. Experiments have shown that the
feeding and growth rates of P. ochraceus reduce greatly when their
body temperatures rise above 23°C (73°F) and that they die when their
temperature rises to 30°C (86°F) [68,69]. is species has a unique
Figure 1: Diversity of different types of sea stars in the marine coastal ecosystem.
Rahman MA, et al., SF Journal of Biotechnology and Biomedical Engineering
2018 | Volume 1 | Edition 2 | Article 1007
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ability to absorb seawater to keep itself cool when it is exposed to
sunlight by a receding tide [70]. It also appears to rely on its arms to
absorb heat, so as to protect the central disc and vital organs like the
stomach [71]. Starsh and other echinoderms are sensitive to marine
pollution [72]. e common starsh is considered to be a bioindicator
for marine ecosystems [73]. eir survival is likely due to the nodular
nature of their skeletons, which are able to compensate for a shortage
of carbonate by growing more eshy tissue [74].
Starsh Evolution
Taxonomic diversity and diversity trends
In terms of total number of species, the Asteroidea (n=1890
species) (Table 1) and the Ophiuroidea (n=2064 species) [75] comprise
the two most diverse classes within the living Echinodermata. Species
counts and names utilized are those nominally accepted by the
World Asteroidea Database as valid (or ‘‘accepted’’ by the database).
Following Blake’s classication with modication by Mah and Foltz
[76] the Valvatacea (Valvatida+Paxillosida) includes the greatest
number of species (n = 1224), followed by the Forcipulatacea (n=393
species), the Velatida (n=145 species) and nally the Spinulosida
(Echinasteridae), which includes 135 species (Table 1) [77]. Mah and
Foltz [76] changed the composition of the Valvatacea to include the
Solasteridae, but even with this dierence (n=51 species), from Blake,
prior versions of the Valvatida included more genera and species
than the Paxillosida [78]. Species diversity is disproportionately
distributed among the 36 families of living Asteroidea (Table 1).
Seven families, Ophidiasteridae, Pterasteridae, Echinasteridae,
Asterinidae, Asteriidae, Goniasteridae and Astropectinidae, each
include more than 100 species. e Goniasteridae (n=256) and
the Astropectinidae (n=243) include the largest number of species
within the Asteroidea. Species are not evenly distributed among
genera. Within the Astropectinidae, Astropecten alone includes
43% (104/243) of the total number of species in the family [79]. e
Goniasteridae includes 65 genera, most of which include multiple
species [80]. At least eight goniasterid genera include more than 10
species. Several genera possess disproportionately high numbers of
species relative to other genera within the family. Henricia includes
some 68% (91/133) of the total known species in the Echinasteridae
[77]. Pteraster (n=45) and Hymenaster (n=50) together account for
82% of the total number of species (n=116) in the Pterasteridae [81].
e aforementioned illustrate the extreme cases, but several more
examples of disproportionately high numbers of species/ family
exist. In nearly every instance of a genus with a disproportionately
high numbers of species, these taxa include a global or widely
distributed range. Astropecten is limited largely to tropical and
temperate settings, but Henricia, Pteraster, and Hymenaster all have
cosmopolitan distributions in cold to temperate water settings.
Starsh Bioactives
Starsh imply a special source of polar steroids of an immense
structural diversity, showing a range of biological activities. e
bioactive compounds such as steroids which act as an integral part
of the cell membrane. e steroidal components namely saponins,
asterosaponins, and astropectenol are the major source of compounds
abundantly found in sea stars [82-88]. A basic study of these facts
reveals the search for “Drugs from the Sea” progresses at the rate of
a 10 percent increase in new compounds per year [79]. e isolation
and characterization of bioactive compounds from the sea stars
Superorder Order Family genera species
Forcipulatacea Forcipulatida Asteriidae 35 178
Heliasteridae 2 9
Stichasteridae 9 28
‘‘Pedicellasteridae’’ 7 32
Zoroasteridae 7 36
Total Forcipulatida 60 283
Brisingida Brisingidae 10 63
Freyellidae 7 47
TOTAL Brisingida 17 110
TOTAL Forcipulatacea 77 393
Spinulosida Echinasteridae 8 133
TOTAL Spinulosida 8 133
Valvatacea Poraniidae 7 22
Valvatida Acanthasteridae 1 2
Archasteridae 1 3
‘‘Asterinidae’’ 25 147
Asterodiscididae 4 20
Asteropseidae 5 6
Chaetasteridae 1 4
Ganeriidae 9 21
Goniasteridae 65 256
Leilasteridae 2 4
Mithrodiidae 2 7
Odontasteridae 6 28
Ophidiasteridae 27 106
Oreasteridae 20 74
Podospherasteridae 1 6
Solasteridae 9 51
Caymanostellidae 2 6
TOTAL Valvatida 187 763
Valvatacea Paxillosida Astropectinidae 26 243
Benthopectinidae 8 69
Ctenodiscidae 1 5
Goniopectinidae 3 10
Luidiidae 1 49
Porcellanasteridae 12 30
Radiasteridae 1 5
Pseudarchasteridae 4 29
TOTAL Paxillosida 56 439
TOTAL Valvatacea 243 1224
Velatida Korethrasteridae 3 7
Myxasteridae 3 9
Pterasteridae 8 116
Concentricycloidea Xyloplacidae 1 3
Total Species 343 1890
Table 1: Breakdown of living taxa among the Neoasteroidea from Foltz and Mah
[75,90].
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in the marine ecosystem is serving a good resource for the human
population to ght against the deadly diseases like cancer.
Elucidation of novel compounds from far eastern sea star
Leptasterias ochotensis illustrated cytotoxic activity towards cancer
cell lines RPMI-7951 and T-47D [82]. Steroidal compounds and
asterosaponins were isolated from cold water star sh Ctenodiscus
crispatus and Culcita novaeguineae, respectively, showing cytotoxicity
against human carcinoma cell lines HepG2 and U87MG ensuing the
apoptosis of the cells, hence playing a signicant role in the anti-
tumor chemotherapy [83,84]. Steroidal compounds were elucidated
from one another species of sea star Astropecten polyacanthus, which
showed cytotoxic activity against the human cancer cell lines HL-60,
PC-3 and SNU-C5 [85]. e crude extracts of the same species of
starsh (A. polyacanthus) also possessed inhibitory eects against the
inammatory components (TNF-α and IL-6) [86]. A polysaccharide
compound extracted from the starsh Asterina pectinifera showed a
chemo-preventive activity against human colon cancer (HT-29) and
human breast cancer by initiating the enzymatic activity which plays a
key task in the carcinogenesis inhibition [87,88]. Few new compounds
of asterosaponins from the starsh Archaster typicus showed cytotoxic
activity against human cervical cancer cell lines and mouse epidermal
cell line [89]. Glycolipids isolated from starsh Narcissia canariensis,
harvested from the coast of Africa showed cytotoxicity against various
adherent human cancerous cell lines (multiple myeloma, colorectal
adenocarcinoma and glioblastoma multiform) [88]. A comparative
study was made between the crude extract from Acanthaster planci
starsh with conventional medicine tamoxifen, a drug used against
the human breast cancer and the extract showed eective apoptotic
activity than the drug tamoxifen in human breast cancer cell line
[90-96]. Hemolytic activity was also studied from various star sh
namely Ophiocoma erinaceus, Acanthaster planci (crown of thorn),
Protoreaster linckii (red knobbed), and Holothuria polii showed
hemolysis when tested against human, chicken, goat and rabbit red
blood cells, hence having a naturally secondary metabolite possessing
hemolytic properties [85-89].
Conclusions
Starsh are some of the unique and most treasured creatures in
the sea, and these fascinating species are the images of the seashore.
ey have profound biological, ecological, cultural, pharmaceutical
and taxonomical signicance. Ecological roles of the starshes in
marine ecosystems are addressed at varied levels. e most prominent
and best-known impact of starshes is due to the common predatory
species in coastal areas. e population dynamics of prey strongly
depends on predation pressure (e.g. the relationship between asteriids
and mussel populations). e rises of falls of the starsh populations
typically depend on the young juvenile recruitment. He uctuation
in settlement success depends on the abundance and health of the
planktonic larvae, and therefore on the phytoplankton enrichment.
Recently starsh have attracted organic chemists, biochemists,
and pharmacologists as a mesmerizing source of marine bioactive
natural products. Numerous secondary metabolites including
steroids, steroidal glycosides, anthraquinones, alkaloids,
phospholipids, peptides, and fatty acids were reported from starsh.
ese biochemical constituents exhibit cytotoxic, hemolytic, antiviral,
antifungal, and antimicrobial, antiaging and antidiabetic activities
and therefore have important implications for the improvement of
general body tone as well as treatment of a number of serious diseases
and health ailments.
Asteroid biodiversity and systematics remains an active area of
research that has brought additional depth to our understanding
of echinoderm evolution and historical changes in the marine
setting. Although much asteroid taxonomy is stable, many new taxa
remain to be discovered with many new species currently awaiting
description. However, until now, the phylogeny of starshes
remains a highly debated topic. Some key issues are central to the
debate, including the monophyly of traditional orders and families
as well as the relationships among the major clades. Morphology-
based and molecular approaches of phylogeny tend to converge,
and future studies should help to minimize the debate. e new
data derived from molecular phylogenetics and the advent of global
biodiversity databases will also present important new springboards
for understanding the global biodiversity and evolution of asteroids.
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