Exam 6 Material (Echinoderms: Type of Deuterostome) Flashcards
What are the five classes of echinoderms?
Crinodea, Astroidea, Ophiuroidea, Echinoidea, Holothuroidea
What are all the classes of echinoderms?
They are all marine
As larvae, what are Echinoderms?
They are bilateral as larvae
As adults, what are echinoderms?
As adults, they form pentaradial bodies (five planes of symmetry)
Do Echinoderms have brains?
No, they don’t have brains
Are Echinoderms dioecious or monoecious?
They are dioecious (have separate male and female individuals)
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)
Pedicellare
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
Hydraulic water vascular system
What is special about an Echinoderm’s tube feet?
Their tube feet have ampulla (pushes fluid into the tube feet)
Which group of Echinoderms are referred to as the feather stars or the sea lilies?
Crinodea
Is the sea lilies (type of Crinoidea) motile or sessile?
They are sessile
Are the feather stars motile or sessile?
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)
How can feather stars eat?
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)
Which group of Echinoderms are considered sea stars?
Astroidea
How many arms can Astroideas have?
Anywhere from 5 to more than 20 arms
What kind of predators are Astroideas?
They are carnivorous predators and scavengers (sometimes a high level predator in some ecosystems)
What kind of prey do Astroideas go after?
Slow and stationary food (they don’t really move themselves)
What kind of circulatory system do Astroideas have?
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)
Which group of Echinoderms are considered brittle stars?
Ophiuroidea
What is special about the arms of Ophiuroidea?
Their arms are much more slender compared to their central disk than astroidea
What is special about the tube feet of Ophiuroidea?
Their tube feet are not used for locomotion but for handling/collecting food
Which group of echinoderms include the sand dollars and sea urchins?
Echinoidea
What is special about Echinoidea’s arms?
They have no arms
What is special about Echinoidea’s skeletal plates?
Their skeletal plates are all fused to form a test
What are Echinoidea covered in?
They are covered in spines
How do the urchins (type of Echinoidea) use their tube feet and spines?
They use their tube feet and spines for locomotion
How do sand dollars use their tube feet and spines?
They use their tube feet and spines for locomotion and digging into the sand
Which group of Echinoderms includes the sea cucumbers?
Holothuroidea
What is special about the Holothuroidea’s body?
Their bodies are an elongated muscular sac
What is special about the Holothuroidea’s mouth?
Their mouth is surrounded by tentacles and those tentacles are modified tube feet
Compared to Echinoderms, what kind of circulatory system do Holothuroideas have?
They have a well-developed circulatory system
How do Holothuroideas trap food?
They trap food inside their mucus-covered tentacles
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)
Evisceration
What is a possible defense mechanism of Holothuroideas?
Some of them can shoot sticky red tubules out of their anus and when they’re attacked (some of the tubules may be toxic)
Which group now shares a branch w/ the Echinoderms and includes the “acorn worms”?
Hemichordata
What are all Hemichordatas?
They are all marine
What makes the mouths of Hemichordatas unique?
They have a ring cilia around their mouth
What makes the bodies of Hemichordatas unique?
Their body is segmented in 3 parts
What are the three body segments of Hemichordatas?
Proboscis, collar, and trunk
What is being described (in Hemichordatas)?:
- Will burrow themselves into the substrate and then will pump water through their pharyngeal slits (do suspension feeding)
How Hemichordatas feed
