“Spiny Skinned Animals” Echinoderms “Spiny Skinned Animals”

Spiny skinned because of the calcium carbonate internal skeleton

Echinoderm Characteristics Radial Symmetry (aboral and oral sides) All marine Most pentamerous No heart, gills, lungs, brain, or eyes Nutrients and gases transported in fluid that fills body cavity Water vascular system Calcium carbonate internal skeleton Nervous system is simple nerve net

Sides of the Echinoderm Oral Side: mouth ampullae- store water ambulacral groove tube-feet Aboral Side: pedicellariae-pinchers anus Madreporite-water opening

Oral Side Ampullae Tube Feet

Aboral Side Pedicellariae (all over surface)

Pedicellariae: tiny pinchers amongst the spines to help keep off parasites & catch bits of food

Water Vascular System (WVS) Hydraulic system containing Tube Feet, attached to appullae which store water for the WVS. Used for: locomotion attachment sensation feeding gas exchange

Water Vascular System Ring Canal Madreporite Radial Canal With Ampullae

Water Vascular System

Water Vascular System Tube Feet

Tube feet and ampulla

Feeding Some carnivorous (sea stars) Some detritus foragers ( urchins & sea cucumbers) Some planktonic feeders (feather stars and basket stars) Many have mouth on oral surface and anus on aboral surface. Sea stars can extend stomach out of mouth and engulf and digest prey Sea cucumbers can eviscerate gut

Sea Star feeding on clam

Reproduction The sexes are separate in most Many release sperm and egg into water Most form pelagic bilaterally symmetrical larvae Asexual reproduction and Regeneration

Sexual Reproduction Fertilization produces pelagic planktonic larvae Sea Star Larvae Brittle Star Larvae Sea Urchin Larvae

Asexual Reproduction by regeneration-all you need is one arm & part of the central disk!

Echinoderms : Five Classes Feather Stars, sea Lillies (Crinoidea) Sea Stars (Astroidea) Brittle Stars, Basket Stars (Ophiuroidea) Sea Urchins, heart urchins, sand dollars (Echinoidea) Sea Cucumbers (Holothuroidea)

Feather Stars and Sea Lilies (Crinoidea) 600 species Crinoids Most ancient class Mouth open up instead of down 5 arms radiate from pentagon shaped body- arms branch into 10 or more arms Tube feet used for filter feeding Sea lilies found in deeper water

Golden Chrinoid CR-269/355 found on coral reefs

Feather Star CR-269/355 here the arms are closed (rolled up) notice the claw-like appendages attaching it to rock

Sea Stars (Asteroidea) 1500 living species Usually 5 rays radiating from central disk Many are active carnivores Excessive numbers can harm marine ecosystems Ability to regenerate entire body from one arm and portion of central disk

West Indian Sea Stars Juvenile and Adult CR-271 / 367 Shallow sea grass beds and sandy flats

West Indian Cushion Star in a Turtle Grass bed

West Indian Cushion Star Four Rays Only

Cushion star Oral view

West Indian Cushion Star Six Rays

Seven Ray Cushion Star

Common Comet Stars CR-275/361 found on reef - notice the different numbers of rays- why the name Comet?

Two-Spined Sea Star Oral View CR-277/363 Notice the ambulacral groove on reach ray

Two-Spined Sea Star Aboral View most often found on sandy bottoms in shallow waters- often burrow into sand

Thorny Sea Stars CR-277/365 found on rock rubble and mangrove roots (same genus as Orange-ridged sea star)

Thorny Sea Star often found hiding under rocks

Brittle Stars, Basket Stars, Serpent Stars (Ophiuroidea) Brittle stars are most numerous (2000 species)!!! Most active echinoderm with swift snake-like movements Under rocks during day & feed on detritus at night Usually 5 thin, flexible arms radiate from central disk Basket stars have complex branched arms used to catch plankton

Blunt Spined Brittle Star CR-283/373

Blunt-Spined Brittle Star CR-283

Red Brittle Star

Banded-Arm Brittle Star CR-285/375

Sponge Brittle Star (CR 281/371)

Sponge Brittle Star on zoanthid CR-281/371

Ruby Brittle Star CR-283/373

Giant Basket Star (closed) CR-287/377

Giant Basket Star (open) open mostly at night filtering planktonic animals

Sea Urchins, Heart Urchins, and Sand Dollars (Echinoidea) “without arms” Test: Calcareous plates fused into shell Often covered with spines- spines often used for locomotion instead of tube feet Most hide during day and are more active at night Sand dollars and heart urchins burrow under the sand during day Most feed on detritus or algae

Diadema Long Spined Sea Urchin CR-287/379

Rock Boring sea Urchin CR-289/380 Aboral View - shorter spines- shallow rocky tidal area

Rock Boring Sea Urchin Oral View

Diadema Rock Boring

Slate Pencil Sea Urchin CR= 291/385 found on sea grass beds and reef ruble

West Indian Sea Egg CR-293/385 found in sea grass beds and shallow reefs

West Indian Sea Egg oral view

Variegated Urchin CR-291/383

Red Heart Urchin CR-293/387 hide under sand during day – when discovered, will “jump” out

Six-Keyhole Sand Dollar CR-295/389 covered with short spine “fuzz”

Sea Cucumbers (Holothuroidea) Elongated soft body – no spines Bilateral symmetry Skeletal plates are very small and buried under leathery body wall Some have tentacle-like tube feet around mouth Mouth in front and anus at rear Defense mechanisms

Three Rowed Sea Cucumber (CR-297/392)

Agassiz Sea Cucumber

Florida Sea Cucumber CR-397 found in shallow sand flats and sea grass beds

Donkey Dung Sea Cucumber CR-297/395 inhabit sandy areas around reefs and sea grass beds

Behavior Sea Cucumber Expelling CuvierianThreads Defense Mechanism (actually Part of the animal’s gut These threads are toxic And can be quickly Regenerated. Behavior

Sea Cucumber Poop

Pearlfish and Sea Cucumbers have an INTERESTING RELATIONSHIP