Cenometra bella

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Cenometra bella
Colobometridae - Cenometra bella.jpg
Cenometra bella in Maldives
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Echinodermata
Class: Crinoidea
Order: Comatulida
Family: Colobometridae
Genus: Cenometra
Species:
C. bella
Binomial name
Cenometra bella
(Hartlaub, 1890) [1]

Cenometra bella is a species of crinoids belonging to the genus Cenometra . They can have up to 30 arms [2] and can be of variable colours but are often characterised by a marked contrast between the extending free-arms and the feathery pinnules (for example, dark brown and white). [2] This species clings to its support and moves around by its feet-like cirri.

Contents

Morphology

Free arms' brown spotted pinnules on a white central ridge. Cenometra bella, pinnulas.jpeg
Free arms' brown spotted pinnules on a white central ridge.

Like many other crinoids, C. bella is visually comparable to both a flowering plant and a sea star. [3] This criter’s evolutionary morphology has remained fairly constant with minimal changes in their appearance. [3]

These small featherstars are predominantly dark brown on their underside. The underside reveals its finger-like brachials and cirri they use to walk and anchor themselves to objects. [4] [5] The centrodorsal plate is the round ‘body’ that holds its brachials and arms together, and averages at 4.181mm in diameter. [5] The mouth is located at the center of this plate. [4] [5] C. bella typically has five short, stiff and stout bifurcating arm bases that radiate from the centrodorsal plate of the comatulid ray, but this number can vary per individual. [4] [5]   These arm bases branch out into two ossicles, giving them a total of ten or more free-arms. [4] [3] [5] The longer non-branching portion of the arms makes up the majority of the arm length, much like many other members of the comatulida order. [6] [5] On average these non-branching feathery arms are 8.5 cm long for an adult C. bella. Each arm has a long white central ridge with dark brown spotted pinnules that project outwards, and slightly taper inwards at the distal end, much like that of a fern plant. [4] [5] Not all, of their arms are regenerating, but every crinoid will have at least a few that are capable of regeneration. [7]

Skeletally, the brachitaxes are composed of two ossicles, with ambulacral appendices. [6] The second pinnule is massive, hard and curved. The basal segment of the proximal pinnules is curved or rounded. [5]

Reproduction & development

There are male and female sexes of C. bella. These gonochoric crinoids shed their ova or sperm from ruptured pinnules into the water. After fertilisation, their embryos grow into larvae that later sink to a substrate surface, like gorgonian coral. The growing larvae, once attached to a surface undergoes metamorphosis into a small crinoid and remains mostly sessile during growth. [3] [8]

Feeding

The beautiful crinoid is a suspension feeder. [8] They filter feed on marine microorganisms like algae, diatoms, and larvae. They also consume marine snow (detritus). This filtration occurs on their cirri, which is linked to the gut near the mouth and anus on the centrodorsal plate. [3]

Behaviour

C. bella on a gorgonian coral Cenometra bella.jpeg
C. bella on a gorgonian coral

These featherstars are mostly sessile, anchoring themselves to hard substrate surfaces or the sea floor using their cirri ‘legs’. However, they are also free-moving creatures capable of traveling short distances to escape their predators or other threats. [3] As nocturnal critters, they partially hide, sessile, within rocks and corals during the day with their mouths oriented upwards. [3] Though their centrodorsal plate remains sheltered during the day as they wait till night to come out and feed, [3] their free-arms can remain fully exposed in a circular fan-like arrangement outside of their habitat, throughout the day. [6] [9]

Distribution & habitat

Cenometra bella Maldives.JPG

Cenometra bella typically occupies shallow tropical waters, [6] [3] living in open-surfaces [9] below depths of 5 meters. [5] They are more commonly located around large coral species in coral reefs, and sometimes found in the intertidal zone. However, in rare cases, they have been found to establish habitat in the deeper ocean [5] [3] (up to 55m [8] ). These featherstars are often exposed on top of a gorgonian coral, [9] under a reef flat, or clinging to sea whips. [8]

This shallow water species is present in the Indo-West Pacific Ocean, [8] thriving around South and South East Asia: India, the Philippines, China, South Japan, the Maldives, South Pacific Islands. [5] C. bella has also been found in the Great Barrier reef. [6]

Threat & survival adaptations

Being mainly sessile creatures, C. bella is highly susceptible to predators like large fish and other marine organisms. [3] They may also lose limbs due to abiotic stressors like great salinity and temperature fluctuations. On average, the feather-star is reported to lose an arm every 8 to12 days. [6]  As a survival mechanism, this crinoid has evolved to be able to lose and regenerate lost limbs, much like a sea-star. Their pinules are also spiked to protect them from predators. [3] In addition, C. bella are able to produce aversive tasting and toxic chemicals to deter predators from consuming their arms [3] [9] that remain exposed out of their habitat throughout the day. The deterrent taste not only provides immediate protection from their predators but also forms long-term negative conditioning to prevent large fish from attacking again. [9]   These antifeedant chemicals also provide the beautiful crinoid's colour. [3]

Related Research Articles

<span class="mw-page-title-main">Echinoderm</span> Exclusively marine phylum of animals with generally 5-point radial symmetry

An echinoderm is any member of the phylum Echinodermata. The adults are recognisable by their radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest entirely marine phylum. The first definitive echinoderms appeared near the start of the Cambrian.

<span class="mw-page-title-main">Crinoid</span> Class of echinoderms

Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their juvenile form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are members of the largest crinoid order, Comatulida. Crinoids are echinoderms in the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. They live in both shallow water and in depths as great as 9,000 meters (30,000 ft).

<span class="mw-page-title-main">Articulata (Crinoidea)</span> Subclass of crinoids

Articulata are a subclass or superorder within the class Crinoidea, including all living crinoid species. They are commonly known as sea lilies or feather stars. The Articulata are differentiated from the extinct subclasses by their lack of an anal plate in the adult stage and the presence of an entoneural system. Articulata first appeared in the fossil record during the Triassic period although other, now extinct crinoid groups, originated in the Ordovician.

<span class="mw-page-title-main">Comasteridae</span> Family of crinoids

Comasteridae is a family of crinoids.

<i>Antedon</i> Genus of crinoids

Antedon is a genus of sessile, stemless crinoids. The genus first appeared in the fossil record in the Cretaceous period.

<span class="mw-page-title-main">Comatulida</span> Order of crinoids

Comatulida is an order of crinoids. Members of this order are known as feather stars and mostly do not have a stalk as adults. The oral surface with the mouth is facing upwards and is surrounded by five, often divided rays with feathery pinnules. Comatulids live on the seabed and on reefs in tropical and temperate waters.

<i>Davidaster rubiginosus</i> Species of crinoid

Davidaster rubiginosus, the orange sea lily, is a species of crinoid in the family Comatulidae. At one time it was classified as Nemaster rubiginosa but the World Register of Marine Species has determined that the valid name is Davidaster rubiginosus. It is found on reefs in the tropical western Atlantic and the Caribbean Sea.

Davidaster discoideus, the beaded crinoid, is a species of feather star in the family Comatulidae. It was previously known as Nemaster discoidea but the World Register of Marine Species has determined that the valid name is Davidaster discoideus. It is found on reefs in the Caribbean Sea and northern coast of South America.

<i>Comaster schlegelii</i> Species of crinoid

Comaster schlegelii, the variable bushy feather star, is a crinoid in the family Comatulidae. It was previously classified as Comanthina schlegeli but further research showed that it was better placed in the genus Comaster. It is found on shallow water reefs in the western Pacific Ocean.

<i>Metacrinus rotundus</i> Species of crinoid

Metacrinus rotundus, the Japanese sea lily, is a marine invertebrate, a species of stalked crinoid in the family Isselicrinidae. It is a species found off the west coast of Japan, and is living near the edge of the continental shelf, around 100–150m deep. This is the shallowest species among the extant stalked crinoids.

<i>Oxycomanthus bennetti</i> Species of echinoderm

Oxycomanthus bennetti, the Bennett's feather star, is a species of crinoid belonging to the family Comatulidae. It is found in shallow water in the Indo-Pacific between northern Australia and southeast Asia.

<i>Himerometra robustipinna</i> Species of crinoid

Himerometra robustipinna is a species of crinoid belonging to the family Himerometridaem first described as Actinometra robustipinna by Philip Herbert Carpenter in 1881.

<i>Antedon mediterranea</i> Species of crinoid

Antedon mediterranea is a species of stalkless crinoid in the family Antedonidae, commonly known as the Mediterranean feather star. It is found on the seabed at moderate depths in the Mediterranean Sea. It is a filter feeder and captures plankton with its long feathery arms.

<span class="mw-page-title-main">Bourgueticrinida</span> Extinct order of crinoids

Bourgueticrinida is an order of crinoids that typically live deep in the ocean. Members of this order are attached to the seabed by a slender stalk and are known as sea lilies. While other groups of crinoids flourished during the Permian, bourgueticrinids along with other extant orders did not appear until the Triassic, following a mass extinction event in which nearly all crinoids died out.

<i>Cenocrinus</i> Genus of crinoids

Cenocrinus is a monotypic genus of stalked crinoids in the family Isselicrinidae. The great West Indian sea lily is the only species in the genus and is found in deep waters in the Caribbean Sea and Gulf of Mexico.

<i>Ptilometra australis</i> Species of crinoid

Ptilometra australis, the passion flower feather star, is a species of crinoid. It is native to the coasts of southeastern Australia where it is found on reefs, in estuaries and bays at depths down to about 110 metres (360 ft).

<i>Leptometra celtica</i> Species of crinoid

Leptometra celtica is a marine invertebrate and species of crinoid or feather star of the Leptometra genus in the family Antedonidae. It is found in the Atlantic Ocean around the coasts of north west Europe. The presence of L. celtica and L. phalangium is considered to be a good indication of nearby shelf breaks, general bottom currents, and areas of high gross productivity as they are suspension-feeders, hence their proliferation in productive environments.

<i>Aporometra wilsoni</i> Species of crinoid

Aporometra wilsoni is a marine invertebrate, a species of crinoid or feather star in the family Aporometridae. It is found in shallow water around the coasts of southern Australia.

<i>Notocrinus virilis</i> Species of crinoid

Notocrinus virilis is a marine invertebrate, a species of crinoid or feather star in the family Notocrinidae. It is found in deep water in the Southern Ocean around the coasts of Antarctica and adjacent islands. A sea snail sometimes parasitizes it.

<i>Aporometra paedophora</i> Species of crinoid

Aporometra paedophora is a marine invertebrate, a species of crinoid or feather star in the family Aporometridae. It was first found at a depth of 22 fathoms off the Manning River on the New South Wales coast. Other specimens were found off the coast of Bunbury, Western Australia at depths between 9 and 15 m. Based on morphological evidence of four specimens of A. paedophora, Helgen & Rouse believe that this may not be a separate species from Aporometra wilsoni.

References

  1. ↑ WoRMS
  2. 1 2 Lisa Kirkendale and Charles Messing An annotated checklist and key to the Crinoidea of Guam and the Commonwealth of the Northern Marianas Islands Micronesica, vol. 35, n. 36, 2003, pg. 523-546
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Feng, Yunjiang, et al. “Crinoids: Ancient Organisms, Modern Chemistry.” Natural Product Reports, vol. 34, no. 6, 2017, pp. 571–584., doi:10.1039/c6np00093b
  4. 1 2 3 4 5 Arguelles, Carmen C, et al. “Identification of Feather Stars (Echinodermata: Crinoidea: Comatulida) at Subic Bay, Zambales, Philippines.” Philippine Journal of Science, vol. 139, no. 1, June 2010, pp. 51–60.
  5. 1 2 3 4 5 6 7 8 9 10 11 Sadhukhan, Koushik, and C. Raghunathan. “New Record of Five Feather Stars (Class: Crinoidea) from Andaman and Nicobar Islands.” Zoological Survey of India, vol. 2, no. 1, 2012.
  6. 1 2 3 4 5 6 Baumiller, Tomasz K., and Forest J. Gahn. “Reconstructing Predation Pressure on Crinoids: Estimating Arm-Loss Rates from Regenerating Arms.” Paleobiology, vol. 39, no. 1, 2013, pp. 40–51., doi:10.1666/0094-8373-39.1.40.
  7. ↑ Baumiller, Tomasz K., and Angela Stevenson. “Reconstructing Predation Intensity on Crinoids Using Longitudinal and Cross-Sectional Approaches.” Swiss Journal of Palaeontology, vol. 137, no. 2, 2018, pp. 189–196., doi:10.1007/s13358-018-0169-6.
  8. 1 2 3 4 5 Jeng, M.-S. 1998 Shallow-water echinoderms of Taiping Island in the South China Sea. Zoological Studies 37(2):137-153.
  9. 1 2 3 4 5 Tinkova, T. V., et al. “Deterrence of Feather Stars (Crinoidea, Comatulida) from Southern Vietnam for the Indo-Pacific Sergeant-Fish Abudefduf Vaigiensis.” Doklady Biological Sciences, vol. 456, no. 1, 2014, pp. 195–198., doi:10.1134/s0012496614030107.
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