Echinoderms are marine animals that have a hard internal skeleton composed of small calcareous plates (ossicles). They have five bodies segments of equal size arranged around a central axis.
Sea stars typically have five arms which widen from tip to base, where they merge into a central disc. Broken arms can be regenerated.
[unidentified sea star]
[unidentified sea star]
[unidentified sea star]
cushion star, Culcita novaeguineae
blue sea star, Linckia laevigata
granular sea star, Choriaster granulatus
multipore sea star, Linckia multifora
[unidentified sea star]
Luzon sea star, Echinaster luzonicus
peppermint sea star, Fromia monilis
[unidentified sea star]
old club sea star, Mithrodia clavigera
bumpy sea star, Gomophia gomophia
[unidentified sea star]
Basket stars have five arms that repeatedly subdivide into many branches. The arms are spred at night to catch zooplankton.
giant basket star, Astroboa nuda
Brittle stars have a small central disk and five arms with numerous spines arranged in rows. The arms can be regenerated.
dark red-spined brittle star, Ophiothrix purpurea
[unidentified brittle star]
[unidentified brittle star]
Crinoids (feather stars) are the most ancient echinoderms. They have small, flattened, pentagon-shaped bodies that immediately fork, giving them a multiple of five arms which resemble feathers. Some are able to swim with coordinated arm movements. Most walk slowly on jointed legs (cirri). Most are hard to identify in the field.
very spiny feather star, Colobometra perspinosa
Bennett's feather star, Oxycomanthus bennetti
[unidentified criniods]
many-rayed feather star, Capillaster multiradiatus
[unidentified crinoids]
Schlegel's feather star, Comaster schlegelii
[unidentified crinoids]
Sea cucumbers have long, thick, cylindrical bodies with a mouth at the front and an anus at the rear. The five-fold internal symmetry shared by all echonoderms is not obvious in a living sea cucumber.
amberfish sea cucumber, Thelenota anax
blackspotted sea cucumber, Bohadschia graeffei
pinkfish sea cucumber, Holothuria edulis
Euapta sp.
Lampert's sea cucumber, Synaptula lamperti
Synaptia sp.
Euapta sp.
Euapta sp.
Opheodesoma sp.
Neothyonidium sp.
Neothyonidium sp.
yellow sea cucumber, Colochirus robustus
Colochirus sp.
red sea apple, Pseudocolochirus tricolor
Sea urchins have external sksletons made up of ten fused plates. Their spherical bodies have long spines and tube feet.
Diadema sp.
magnificent fire urchin, Asthenosoma ijimai
variable fire urchin, Asthenosoma varium
Diadema sp.
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Last modified 17 October 2019