ECHINODERMATA Flashcards
Class?
sea lilies
Class Crinoidea
Class?
Sea stars
Class Asteroidea
Class?
brittle stars and basket stars
Class Ophiuroidea
Class?
Sea urchins and sand dollars
Class Echinoidea
Class?
sea cucumbers
Class Holothuroidea
Type of symmetry?
Bilateral as larva
pentamerous radial as adults
What are the podia?
tube feet
Which arms (ambulacra) are the bivium?
Arms C and D
*arms lettered with reference to the madreporite. Ambulacrum opposite is A then proceed counterclockwise.
Which arms (ambulacra) are the trivium?
A, B and E
*arms lettered with reference to the madreporite. Ambulacrum opposite is A then proceed counterclockwise.
Function of mutable collagenous tissues?
Connective tissue that can change properties very quickly.
Under neuronal control
Normally rigid but can soften quickly.
Allows echinoderms to maintain fixed postures with minimal metabolic energy.
Describe the Fluid of the water vascular system
Fluid similar to seawater but has coelomcytes and organic molecules.
How is the fluid within the water vascular system moved?
Cilia
What is the water vascular system
Fluid-filled canals for internal
transport and locomotion.
Location and function of the madreporite?
On aboral surface. Grooved with ciliated epidermis. May allow seawater into vascular system.
What is the ampulla?
looks like the turkey baster
under madreporite connected to water vascular system and hemal system.
What does the stone canal do?
connects ampulla to the water vasc system and connects to the ring canal
What does the ring canal do?
Leads to radial canals in each arm. Also has Polian vessicles
(maintain internal pressure) and Tiedemann’s bodies (produce coelomcytes).
Where do radial canals lead?
to lateral canals
Where do lateral canals lead?
pass thru pores in the skeletal plates and end in the tube feet
What is the function of tube feet?
Tube feet used for locomotion, prey capture, adherence to substratum.
Terminal tube feet are chemosensory.
Also aid in gas exchange
How do they support their bodies?
Calcareous endoskeleton with different degrees of calcification.
Holothuroids have very muscular body walls.
How do Crinoids move?
They walk on the tips of their arms. Some swim.
How do Asteroids move?
crawl with tube feet
How do Ophiuroids move?
use flexible arms for crawling.
How do urchins move?
Use tube feet and moveable spines
How do sand dollars move?
use spines to burrow in sand
How do cucumbers move?
crawl on podia of trivium or by
muscular action of the body wall
How do Crinoids feed?
Filter feed with oral side up and arms and pinnules outstretched.
Food particles brought to mouth via cilia in ambulacral grooves.
How do asteroids feed?
Most are predators and scavengers. Eversible portion of stomach (cardiac stomach) extruded onto or into prey.
How do Ophiuroids feed?
Predators, scavengers, filter feeders, deposit feeders.
Food collected and passed along podia and spines to mouth.
*Digestive system reduced with no anus.
How do Echinoids feed?
Herbivores, suspension feeders, detritovores.
Urchins have Aristotle’s lantern. Hard plates and muscles that control protraction of five teeth.
Teeth scrape algae off rocks and take bites of macroalgae. Can excavate holes in rocks.
How do Holothuroids feed?
Suspension and deposit feeders.
Extend mucus-covered buccal tentacles into water. Tentacles are pushed into mouth one at a time.
What are Cuverian Tubules and which class are they present in?
Blind sticky tubes at base of respiratory tree.
Entangle predators.
Present in Holothuroids
How do they achieve internal transport?
Internal transport by coeloms, water vascular system, and hemal systems.
What is a hemal system?
An array of canals and spaces enclosed within coelomic channels called perihemal sinuses. Parallels water vascular system.
Probably helps distribute respiratory gases and nutrients.
Gas exchange in Holothuroids?
Holothuroids have respiratory trees. Water is actively pumped by muscular hind end. Gases picked up by coelom and hemal system.
How do they osmoregulate?
Osmoconformers.
Waste is usually ammonia lost across podia and dermal branchia.
How do they reproduce asexually?
Most capable of regenerating lost parts.
Holothuroids regenerate intestines and respiratory trees.
Asteroids and ophiuroids regenerate lost arms and suckers.
Gonochoristic or hermaphroditic?
Most gonochoristic
Direct or indirect development?
Both - Free spawning with indirect development to brooding with direct development.
