Exam 6 Material (Echinoderms: Type of Deuterostome)

Question 1

What are the five classes of echinoderms?

Answer 1

Crinodea, Astroidea, Ophiuroidea, Echinoidea, Holothuroidea

Question 2

What are all the classes of echinoderms?

Answer 2

They are all marine

Question 3

As larvae, what are Echinoderms?

Answer 3

They are bilateral as larvae

Question 4

As adults, what are echinoderms?

Answer 4

As adults, they form pentaradial bodies (five planes of symmetry)

Question 5

Do Echinoderms have brains?

Answer 5

No, they don’t have brains

Question 6

Are Echinoderms dioecious or monoecious?

Answer 6

They are dioecious (have separate male and female individuals)

Question 7

What is being described (are present in Echinoderms)?:
- Little modified spines
- Can actually pick up debris and move them off the bodies of the echinoderm)

Answer 7

Pedicellare

Question 8

What is being described (present in deuterostomes)?:
- Unique to Echinoderms
- A series of fluid-filled canals and that can use those for locomotion, feeding, gas exchange, etc.
- Includes the tube feet

Answer 8

Hydraulic water vascular system

Question 9

What is special about an Echinoderm’s tube feet?

Answer 9

Their tube feet have ampulla (pushes fluid into the tube feet)

Question 10

Which group of Echinoderms are referred to as the feather stars or the sea lilies?

Answer 10

Crinodea

Question 11

Is the sea lilies (type of Crinoidea) motile or sessile?

Answer 11

They are sessile

Question 12

Are the feather stars motile or sessile?

Answer 12

Feather stars can move (but they often stay put for a while before moving again) (they can kind of swim and can move away from predators)

Question 13

How can feather stars eat?

Answer 13

They can eat by flapping their arms out into the water column and they capture food on their tube feet (covered in mucus) carries to food to the oral surface (which is facing up unlike other classes)

Question 14

Which group of Echinoderms are considered sea stars?

Answer 14

Astroidea

Question 15

How many arms can Astroideas have?

Answer 15

Anywhere from 5 to more than 20 arms

Question 16

What kind of predators are Astroideas?

Answer 16

They are carnivorous predators and scavengers (sometimes a high level predator in some ecosystems)

Question 17

What kind of prey do Astroideas go after?

Answer 17

Slow and stationary food (they don’t really move themselves)

Question 18

What kind of circulatory system do Astroideas have?

Answer 18

They have a poorly developed circulatory system (gas and waste exchange occurs across their dermal gills) (can also have waste exchange through the tube feet as well as locomotion)

Question 19

Which group of Echinoderms are considered brittle stars?

Answer 19

Ophiuroidea

Question 20

What is special about the arms of Ophiuroidea?

Answer 20

Their arms are much more slender compared to their central disk than astroidea

Question 21

What is special about the tube feet of Ophiuroidea?

Answer 21

Their tube feet are not used for locomotion but for handling/collecting food

Question 22

Which group of echinoderms include the sand dollars and sea urchins?

Answer 22

Echinoidea

Question 23

What is special about Echinoidea’s arms?

Answer 23

They have no arms

Question 24

What is special about Echinoidea’s skeletal plates?

Answer 24

Their skeletal plates are all fused to form a test

Question 25

What are Echinoidea covered in?

Answer 25

They are covered in spines

Question 26

How do the urchins (type of Echinoidea) use their tube feet and spines?

Answer 26

They use their tube feet and spines for locomotion

Question 27

How do sand dollars use their tube feet and spines?

Answer 27

They use their tube feet and spines for locomotion and digging into the sand

Question 28

Which group of Echinoderms includes the sea cucumbers?

Answer 28

Holothuroidea

Question 29

What is special about the Holothuroidea’s body?

Answer 29

Their bodies are an elongated muscular sac

Question 30

What is special about the Holothuroidea’s mouth?

Answer 30

Their mouth is surrounded by tentacles and those tentacles are modified tube feet

Question 31

Compared to Echinoderms, what kind of circulatory system do Holothuroideas have?

Answer 31

They have a well-developed circulatory system

Question 32

How do Holothuroideas trap food?

Answer 32

They trap food inside their mucus-covered tentacles

Question 33

What is being described (present in Holothuroideas)?:
- When conditions become unfavorable, Holothuroideas will spit out all their guts, and when things get better, they will regrow their guts (b/c the digestive tract takes a lot of energy to operate)

Answer 33

Evisceration

Question 34

What is a possible defense mechanism of Holothuroideas?

Answer 34

Some of them can shoot sticky red tubules out of their anus and when they’re attacked (some of the tubules may be toxic)

Question 35

Which group now shares a branch w/ the Echinoderms and includes the “acorn worms”?

Answer 35

Hemichordata

Question 36

What are all Hemichordatas?

Answer 36

They are all marine

Question 37

What makes the mouths of Hemichordatas unique?

Answer 37

They have a ring cilia around their mouth

Question 38

What makes the bodies of Hemichordatas unique?

Answer 38

Their body is segmented in 3 parts

Question 39

What are the three body segments of Hemichordatas?

Answer 39

Proboscis, collar, and trunk

Question 40

What is being described (in Hemichordatas)?:
- Will burrow themselves into the substrate and then will pump water through their pharyngeal slits (do suspension feeding)

Answer 40

How Hemichordatas feed