Phylum Echinodermata Flashcards
Symmetry
Penta-radial adults with bilateral larva
What kind of larva?
Bilaterally symmetric
- Pluteus
- Bipinnaria
- Auricularia
How do echinoderms respire
Dermal Branchiae or tube feet
- Sea cucumbers have respiratory tree
- Brittle stars have bursae
7 Echinoderm characteristics
- Deuterstome
- Eucoelomate
- Internal skeleton of calcareous ossicles
- No cephalization (secondarily lost)
- No excretory organs
- Dioecious
- External fertilization
Which class may brood larva?
Ophiuroidea may sometimes brood larva in bursae
Protostome vs. Deuterstome development
- Fate of Blastopore (determinant or indeterminant)
- Spiral vs. Radial cleavage
- Schizocoelous vs. enterocoelus (Mesoderm split vs. outpockets of archenteron form coelom)
What are the 5 classes in Phylum Echinodermata?
- Asteroidea
- Crinoidea
- Holothuroidea
- Echinoidea
- Ophiuroidea
How many arms does Asteroidea have?
5 or more that merge gradually with a central disc
What is the skeleton of Asteroidea
endoskeleton of ossicles bound by connective tissue
What are ossicles?
Internal calcareous skeleton (plates in asteroidea)
Does asteroidea have spines?
Yes, tubercules on ossicles with spines
Where are the tube feet located in Asteroidea?
along the abulacral grooves, topped with suckers
What are pedicellariae?
Pincher-like appendages on the skin surface that are used for defense and keeping the surface skin clear of debris
- Found in Asteroidea and Echinoidea
What are papulla?
Used for gas exchange, found on skin surface
Where is the madreporite on Asteroidea?
The aboral surface
How do sea stars feed?
- Feed on molluscs, crustaceans, polychaetes, echinoderms, and other inverts
- Digestion is external by everting stomach, rarely internal
- Larger waste material discharged by the mouth
What is the sea star habitat?
Shallow waters and lower intertidal on rock, sand or mud substrates
What are the larval types of asteroidea?
Bipinnaria and then brachiolaria planktonic larva
How many arms do brittle stars have?
5 arms set off sharply from central disc and made of a column of ossicles connected by muscles and covered by plates
Where is the madreporite in Ophiuroidea?
The oral surface
What are bursae
Pockets between the arms of ophiuroidea that are used for respiration, brooding larvae and possibly filter feeding
Characteristics of Ophiuroidea
- 5 arms set off from central disc
- No pedicellariae or papula
- Ambulacral groove closed and covered w/ ossicles
- No suckers on tube feet
- Madreporite on oral surface
- No anus or intestine
- Spines located on the sides of the arms
- five pairs of bursae between each arm
- Great powers of regeneration
Ophiuroidea habitat
Benthic marine at all depths and substrates
Ophiuroidea
Brittle stars
Ophiuroidea feeding
suspension feeders using mucus on tube feet, or browsers/snaggers
Ophiuroidea reproduction
dioecious external fertilization ophiopluteus larva gonads empty into the bursae some species brood young in bursae and release juvenilles
What has happened to the ossicles in Echinoidea?
Fused to form the internal skeleton known as a test
Where are the anus and madreporite on the echinoidea?
The aboral surface
What is Aristotle’s lantern?
The specialized feeding apparatus in Echinoidea that is most well developed in the urchins
and has 5 teeth
What is the feeding mode of the Echinoidea?
Algal grazers using Aristotle’s lantern or filter /detritus feeders with mucous on tube feet
Echinoidea reproduction
dioecious, external fertilization, echinopluteus planktonic larva
Echinoidea habitat
Shallow to deep sea, urchins like hard substrate, dollars and heart urchins like sandy substrate
Why is there sand in sand dollars?
The sand in sand dollars is used for weight balance.
What is the issue with japanese eel grass?
It is stabilizing sand and reducing sand dollar habitat
Characteristics of class Holothuroidea
- Elongated aboral-oral axis
- Reduced ossicles scattered within the epidermis
- Ambulacral region is well developed on one side
- 10 to 30 tentacles used mostly for filtering
- Respiratory tree for gas exchange
- Eviscerates internal organs to distract predators
Holothuroidea feeding mechanisms
suspension or deposit feeding with tentacles modified for feeding mode that can be retractable
Holothuroidea Reproduction
dioecious, external fertilization, free swimming Auricularia larvae or brooded on female
Holothuroidea Habitat
Hard or soft substrate intertidal to super deep
Characteristics of Class Crinoidea
- Body disc with leathery skin and calcareous plates
- 5 flexible arms branched at base bearing pinnules
- No madreporite, spines, or pedicellariae
- Upper surface is oral bearing mouth and anus
- Tentaculate tube feet in abulacral groove
Crinoidea Feeding
Use tube feet and mucous net to catch small organisms with ciliated ambulacral groove that transports food to the mouth
Crinoidea Reproduction
Dioecious with free swimming Dollolaria larvae
Crinoidea Habitat
Shallow tropical pacific and caribbean but also many deep water species
What are the issues with sea urchin fisheries?
- Urchin barrens were thought to reduce diversity and so urchins were heavily fished. However, it wasn’t the barrens that were often fished and because urchins in barrens don’t have well developed gonads, the populations greatly decreased.
