Phylum Echinodermata

Question 1

Where can Class Asteroidea be found?

Answer 1

-along shorelines and may aggregate on rocks
-some live on muddy or sandy bottoms or coral reefs

Question 2

Describe the form and function of Class Asteroidea

Answer 2

-flattened body and flexible
-pigmented and ciliated epidermis
-aboral surface covered with spines
-pedicellariae at bases of spines

Question 3

What is Papulae

Answer 3

-soft projections lined with peritoneum
-respiratory gases and ammonia diffuse across the papulae and tube feet

Question 4

What are coelomocytes

Answer 4

pick up wastes and migrates to exterior

Question 5

Describe the internal anatomy of class Asteroidea

Answer 5

-large body cavity - one coelomic compartment filled with fluid
-fluid contains amoebocytes
-circulation via ciliated peritoneal lining of coelem
-fluid circulates around internal organs and into papulae

Question 6

Describe the mesodermal endoskeleton of the class Asteroidea

Answer 6

-small calcareous plates (ossicles) bound together by an unusual form of mutable collagen
-ossicles penetrated by meshwork of spaces filled with fibers and dermal cells (stereom)

Question 7

-This system is a second coelomic compartment
-System of canals, tube feet, and dermal ossicles
-Functions in locomotion, food-gathering, respiration, and excretion
-Opens to outside at madreporite on aboral side

Answer 7

Water-Vascular System

Question 8

Water-Vascular System

Answer 8

-Opens to outside at madreporite on aboral side
-Madreporite > stone canal > ring canal that encircles the mouth
-Radial canals diverge from ring canal and extend into each ray
4 or 5 pairs of Tiedemann’s bodies attach to ring canal and may produce coelomocytes

Question 9

Feeding and Digestive System of class Asteroidea

Answer 9

-mouth>short esophagus > large double stomach
-some lack intestine and anus

Question 10

Reproductive System of class Asteroidea

Answer 10

-Sexes separate in most
-Paired gonads in each interradial space
-External fertilization

Question 11

Regeneration of Class Asteroidea

Answer 11

-Cast off injured arms and regenerate new ones - autotomy
-An arm can regenerate a new sea star if at least one-fifth of central disc is present

Question 14

Class Ophiuroidea

Answer 14

-live on hard or sandy bottoms where little light penetrates
-browsers and suspension feeders
-regeneration and autonomy more pronounced than in sea stars

Question 15

Describe Class Echinoidea

Answer 15

-Lack arms but their tests show five-part symmetry
-Ambulacral areas folded up to area of the anus
-Most with hemispherical shape, radial symmetry and long spines
-Regular urchins move by tube feet
Irregular urchins move by their spines
-Echinoids occur from intertidal regions to deep ocean

Question 16

-Spines articulate on “ball-and-socket” joints moved by small muscles at the bases
-Some species have pedicellariae with poison glands - toxin paralyzes small prey

Answer 16

Class Echinoidea

Question 17

Complex set of chewing structures of Class Echinoidea

Answer 17

Aristotle’s lantern

Question 18

Describe Class Holothuroidea

Answer 18

-Greatly elongated in the oral-aboral axis
-Ossicles greatly reduced and body is soft
-Some species crawl on the ocean bottom, others are found under rocks or burrow

Question 19

-Body wall leathery with microscopic ossicles embedded
-In some, locomotor tube feet are distributed to all five ambulacral areas
Most have them only on the ambulacra that faces the substratum (sole)
All tube feet, except oral tentacles, absent in burrowing forms

Answer 19

Class Holothuroidea

Question 20

Describe Digestive and Excretory of Class Holothuroidea

Answer 20

-Digestive system and respiratory tree opens into a cloaca
-Madreporite lies free in the coelom
-Respiratory tree also serves for excretion
-Gas exchange also occurs through the skin and tube feet

Question 21

Describe Feeding/Defense of Class Holothuroidea

Answer 21

-Some trap particles on the mucus of tentacles
-Others graze sea bottom with tentacles
-Cast out part of viscera when irritated
-Sticky and have toxins
-Must regenerate these tissues

Question 22

Describe Class Crinoidea

Answer 22

-Sea lilies have a flower-shaped body at tip of a stalk
-Feather stars have long, many-branched arms
-Have primitive characters
-More numerous in fossil record
-Unique feature – sessile
-Many crinoids are deep-water species
-Feather stars are found in more shallow water

Question 23

Describe Form of Class Crinoidea

Answer 23

-Body disc or calyx covered with a leathery skin or tegument of calcareous plates
-5 arms branch to form more arms, each with lateral pinnules
-Calyx and arms form a crown
-Stalk (if present) formed of plates
-Madreporite, spines, and pedicellariae absent

Question 24

Describe Function of Class Crinoidea

Answer 24

Oral surface with mouth that opens into esophagus and intestine
Ambulacral grooves with tube feet (podia) extend from mouth along arms and pinnules
Has a water-vascular system, an oral ring, and a radial nerve to each arm