Echinodermata

Question 1

Name the 9 traits of Phylum Echinodermata

Answer 1

1. Coelomate deuterostomes
2. Symmetry - pentaradial
3. Decentralized nervous system
4. Complete gut - blastopore becomes the anus, not the mouth. They have a perivisceral coelom around their gut
5. Mesodermal endoskeleton - built from ossicles (porous) of CaCO3
6. Water vascular system - true coelom
7. Hemal system - coelom
8. No excretory system - lack of the excretory system may be why they’re only marine
9. All marine (mostly benthic)

Question 2

What is one synapomorphy of Echinodermata?

Answer 2

1. Mesodermal endoskeleton

Question 3

What are the 5 major subgroups of Echinodermata?

Answer 3

1. Crinoidea - feather stars and sea lilies
2. Ophiuroidea - brittle stars and basket stars
3. Asteroidea - sea stars; predatory
4. Echinoidea - urchins and sand dollars
5. Holothuroidea - sea cucumbers

Question 4

Crinoidea - tube feet

Answer 4

no suckers, just flesh and sticky tissue. It facilitates gas exchange and catches food

Question 5

Crinoidea - ciliated grooves

Answer 5

allows for food flow from the tube foot to the ciliates grooves, to the mouth

Question 6

Crinoidea - pinnules

Answer 6

side branches (more SA)

Question 7

Crinoidea - calyx

Answer 7

contains the gut

Question 8

Crinoidea - cirri

Answer 8

thin, noodly-like extension from the body

Question 9

Do Crinoidea have any gonads or suckers?

Answer 9

No

Question 10

Ophiuroidea

Answer 10

they are selective deposit feeders that use tube feet to feed. Basket starts are predatory

Question 11

Ophiuroidea - branches

Answer 11

these branches create intense complexity because it creates tons of SA

Question 12

Ophiuroidea - madreporite

Answer 12

located on the oral side of the animal. Allows sea water to be exchange in the water vascular system

Question 13

Ophiuroidea - bursal slit

Answer 13

highly ciliated chamber that allows H2O to enter/exit. Allows for gas exchange

Question 14

Ophiuroidea - vertebra

Answer 14

CaCO3 ossicles for structural support

Question 15

Ophiuroidea - tube foot

Answer 15

sticky and ciliated

Question 16

Do Ophiuroidea have suckers and a complete gut?

Answer 16

they don’t have suckers and they don’t have a complete gut. They have an incomplete gut because their anus is lost

Question 17

Echinoidea - madreporite

Answer 17

pressure radiation. It adjusts H2O pressure

Question 18

Echinoidea - movable spine

Answer 18

protects itself by wedging itself into tight spaces, therefore, the long spines must be movable. Their shorter spines are fixed

Question 19

Echinoidea - ambulacral region

Answer 19

region where there are tube feet

Question 20

Echinoidea - ocular plate

Answer 20

optical tube foot

Question 21

Echinoidea - genital plate

Answer 21

this is where the gonopore is located. One of the genital plates function as the madreporite

Question 22

Echinoidea - interambulacral region

Answer 22

regions without tube feet

Question 23

Echinoidea - stone canal

Answer 23

connects the ring canal to the madreporite. Helps regulate liquid fluid and is a part of the water vascular system. Reinforced with CaCO3

Question 24

Echinoidea - ring canal and radial canal

Answer 24

there are 5 radial canals that are connected to the ring canal

Question 25

Echinoidea - mouth

Answer 25

Aristotle's latern. Used for biting

Question 26

Holothuroidea - tentacles and tube foot

Answer 26

modified foot used for feeding. Captures food and brings it to the mouth has tube feet

Question 27

Holothuroidea - madreporite and stone canal

Answer 27

their madreporite is internal. Their stone canal connects the madreporite to the ring canal

Question 28

Holothuroidea - polian vesicle

Answer 28

maintain pressure in the system and hold reserve supplies of fluid

Question 29

Holothuroidea - ring canal and radial canal

Answer 29

has 5 radial canals connected to the ring canal

Question 30

Holothuroidea - viscera

Answer 30

contains the internal organs

Question 31

Holothuroidea - cuvierian tubules

Answer 31

defense mechanism that protects their anus from potential predators (tropical adaptation)

Question 32

Holothuroidea - respiratory tree

Answer 32

used for gas exchange

Question 33

Asteroidea - polian vesicles

Answer 33

reserve of water for when the animal withdraws their tube feet

Question 34

Asteroidea - ring canal and radial canal

Answer 34

there are 5 radial canals connected to the ring canal

Question 35

Asteroidea - gonads

Answer 35

they have 10 gonads in total

Question 36

Asteroidea - medreporite and stone canal

Answer 36

stone canal connects the ring canal to the madreporite. The madreporite is connected to the interamulacral region

Question 37

Asteroidea - madreporite and stone canal

Answer 37

stone canal connects the ring canal to the madreporite. The madreporite is in the interambulacral region the madreporite acts as a water filter and supplied water to the water vascular system to move

Question 38

Asteroidea - gonopore

Answer 38

if male, it'll spray sperm through the male gonopore. Females will release eggs here

Question 39

Asteroidea - sceptical tube foot

Answer 39

senses light

Question 40

Asteroidea - dermal gill

Answer 40

releases CO2 and NH3, and takes up O2. Functions in gas exchange

Question 41

Asteroidea - perivisceral coelom

Answer 41

completely enveloped in mesoderm, therefore, it's a true coelom

Question 42

Asteroidea - peritoneum

Answer 42

mesodermally derived and envelopes the internal organs. It's like a sac

Question 43

Asteroidea - digestive gland (pyloric cecum)

Answer 43

releases enzymes and absorbs nutrients from food

Question 44

Feeding and digestion of each subgroup

Answer 44

1. Echinoids: grazers, suspension feeders, selective deposit feeders 2. Holothuroids: suspension feeders, selective deposit feeders, direct deposit feeders 3. Ophiuroids: selective deposit feeders, predators 4. Crinoids: suspension feeders 5. Asteroids: predators, scavengers, detritus feeders, suspension feeders

Question 45

Gas exchange of each subgroup

Answer 45

asteroids and echinoids use dermal gills holothuroids use their respiratory tree Ophiuroids use their bursae