Sea Cucumber
Classification:
Phylum- Echinodermata Presence of spines on body
Class
- Holothuroidea Body cylindrical with bilateral
symmetry
Order- Aspidochirotida Body wall tough and muscular
Type- Sea Cucumber Body elongated with bilateral
symmetry
Characters:
1. Body elongated, vermiform and bilaterally symmetrical.
2. Tube feet scattered all over the body.
3. Dorsal tube feet pointed.
4. 20-30 oral tentacles are present anteriorly.
5. Ventral tube feet with suckers.
Brittle Star
Classification:
Phylum- Echinodermata Presence of spines on body
Class
- Stelleroidea Long slender arm containing
open ambulacral groove
Order- Oegophiurida Presence of five simple, slender,
jointed and brittle arms
Type- Brittle Star Flat disc covered by scales
and radial shields.
Characters:
1. Body flattened, pentamerous and star shaped.
2. It shows 5 long, slender, brittle arms
3. Spines on the body are short, cilia like and downwardly
directed.
4. Arms bear open ambulacral grooves on ventral side.
5. Oral and aboral surfaces are distinct.
Sea Star
Classification:
Phylum- Echinodermata Presence of spines on
body
Class
- Asteroidea Pentagonal body with
flattened central disc
Order- Forcipulata Marginal plates
not prominent
Genus- Asterias Body
star shaped with radial symmetry
Species- rubencs Ambulacral
spines with pedicellariae
Characters:
1. Commonly called as star fish.
2. Body pentagonal star shaped with radial symmetry.
3. Ambulacral grooves are open and bear tube feet in 2 rows.
4. Mouth is on the oral surface and anus is on the aboral
surface.
5. Tube feet are provided with the terminal suckers hence they
act as locomotary organs.
Sea Urchin
Classification:
Phylum- Echinodermata Presence of spines on body
Class
- Echinoidea Body globular, oval
Order- Echinoida Testa globular and rigid
Type- Sea urchin Body with flat oral and dome
shaped
aboral surface
Characters:
1. Body nearly spherical with flat oral and dome shaped aboral
surface.
2. Calcareous plates are present on body surface which act as
exoskeleton called as test.
3. Whole surface of test is covered with movable spines except
mouth and anal region.
4. Tube feet are arranged in rows in ambulacral grooves
5. External gills are present.
6. Spines are of same size.
Sea Lily/ Feather Star
Classification:
Phylum- Echinodermata Presence of spines on body
Class
- Crinoidea Presence of stalk and
branched arms
Order- Commatulida Arms usually branched bearing
pinnules
Type- Sea lily Arms 10, elongated and slender
Characters:
1. These animals are usually stalked with movable and branched
arms.
2. Generally 10 long, slender arms are present.
3. Both mouth and anus are present on oral surface.
4. Oral surface is leathery and with numerous calcareous
plates.
5. Each arm contains the double series of pinnules.
6. Young stages are stalked while later stages are free
swimming.
