Lecture 11

Question 1

what features differentiate echinoderms and what anatomical features are unique to them

Answer 1

water vascular system, tube feet (podia) , internal calcareous endoskeleton (ossicles), adult pentameric radial symmetry,

Question 2

describe the water vascular system and its functions

Answer 2

unique to echinoderms

origionally used for feeding, now used for locomotion and gas exchange (tube feet have thin memranes)

one radial canal/arm

paired lateral canal connecting radial canal and ampulla ( muscularized suction feet)

tube foot: connected to ampulla, projects out through the body wall (suction cups)

ring canal incircles digestive tract

ampulla used for movement and eating

Question 3

describe skeletal elements present in echinoderms

Question 4

indicate why some echinoderms are considered keystone species

Answer 4

increase biodiversity in their habitats

Question 5

phylum echinodermata

Answer 5

sea stars, urchins, sand dollars, sea cucumbers…

marine

present at all depths

pentaradial symmetry (oral axis) ; bilateral larva

water vascualer system

calacereous ossicles derived brom mesoderm

nervous system including nerve ring, radial nerves and nerve net

Question 6

digestion: echinoderms

Answer 6

oral cardiac stomach

anus is rarely used, most waste is excreted through the mouth

Question 7

class asteroidea

Answer 7

standard sea stars

benthic redators

most diverse in warm climates

effects level of diversity within their ecosystem

Question 8

class ophiuroidea

Answer 8

snake, tail

branched or unbranched arms

dermal branchia and pedicellariae (pincer like organs) absent

madreporite on oral aspect

water vascular system is not used for movement

ambulacral groove closed by aboral ossicle

no extensions of gut int arms

arms are highly muscularized and used for movement

Question 9

class echinoidea

Answer 9

urchins and sand dollars

interambulcaral plates have spines

ambulacral plate have tube feet

Question 10

class holothuroidea

Answer 10

sea cucumbers

no shell

5 radial vascular canals

slow growers

respiratory tree is attached to the but

vascular system is filled with celomic fluid

Question 11

class Crinoidea

Answer 11

sea lilies and feather stars

few species left (very primative)

swim by opening and closing thei arms