Echinodermata Flashcards
Name the 9 traits of Phylum Echinodermata
- Coelomate deuterostomes
- Symmetry - pentaradial
- Decentralized nervous system
- Complete gut - blastopore becomes the anus, not the mouth. They have a perivisceral coelom around their gut
- Mesodermal endoskeleton - built from ossicles (porous) of CaCO3
- Water vascular system - true coelom
- Hemal system - coelom
- No excretory system - lack of the excretory system may be why they’re only marine
- All marine (mostly benthic)
What is one synapomorphy of Echinodermata?
- Mesodermal endoskeleton
What are the 5 major subgroups of Echinodermata?
- Crinoidea - feather stars and sea lilies
- Ophiuroidea - brittle stars and basket stars
- Asteroidea - sea stars; predatory
- Echinoidea - urchins and sand dollars
- Holothuroidea - sea cucumbers
Crinoidea - tube feet
no suckers, just flesh and sticky tissue. It facilitates gas exchange and catches food
Crinoidea - ciliated grooves
allows for food flow from the tube foot to the ciliates grooves, to the mouth
Crinoidea - pinnules
side branches (more SA)
Crinoidea - calyx
contains the gut
Crinoidea - cirri
thin, noodly-like extension from the body
Do Crinoidea have any gonads or suckers?
No
Ophiuroidea
they are selective deposit feeders that use tube feet to feed. Basket starts are predatory
Ophiuroidea - branches
these branches create intense complexity because it creates tons of SA
Ophiuroidea - madreporite
located on the oral side of the animal. Allows sea water to be exchange in the water vascular system
Ophiuroidea - bursal slit
highly ciliated chamber that allows H2O to enter/exit. Allows for gas exchange
Ophiuroidea - vertebra
CaCO3 ossicles for structural support
Ophiuroidea - tube foot
sticky and ciliated
Do Ophiuroidea have suckers and a complete gut?
they don’t have suckers and they don’t have a complete gut. They have an incomplete gut because their anus is lost
Echinoidea - madreporite
pressure radiation. It adjusts H2O pressure
Echinoidea - movable spine
protects itself by wedging itself into tight spaces, therefore, the long spines must be movable. Their shorter spines are fixed
Echinoidea - ambulacral region
region where there are tube feet
Echinoidea - ocular plate
optical tube foot
Echinoidea - genital plate
this is where the gonopore is located. One of the genital plates function as the madreporite
Echinoidea - interambulacral region
regions without tube feet
Echinoidea - stone canal
connects the ring canal to the madreporite. Helps regulate liquid fluid and is a part of the water vascular system. Reinforced with CaCO3
Echinoidea - ring canal and radial canal
there are 5 radial canals that are connected to the ring canal
Echinoidea - mouth
Aristotle’s latern. Used for biting
Holothuroidea - tentacles and tube foot
modified foot used for feeding. Captures food and brings it to the mouth
has tube feet
Holothuroidea - madreporite and stone canal
their madreporite is internal. Their stone canal connects the madreporite to the ring canal
Holothuroidea - polian vesicle
maintain pressure in the system and hold reserve supplies of fluid
Holothuroidea - ring canal and radial canal
has 5 radial canals connected to the ring canal
Holothuroidea - viscera
contains the internal organs
Holothuroidea - cuvierian tubules
defense mechanism that protects their anus from potential predators (tropical adaptation)
Holothuroidea - respiratory tree
used for gas exchange
Asteroidea - polian vesicles
reserve of water for when the animal withdraws their tube feet
Asteroidea - ring canal and radial canal
there are 5 radial canals connected to the ring canal
Asteroidea - gonads
they have 10 gonads in total
Asteroidea - medreporite and stone canal
stone canal connects the ring canal to the madreporite. The madreporite is connected to the interamulacral region
Asteroidea - madreporite and stone canal
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
Asteroidea - gonopore
if male, it’ll spray sperm through the male gonopore. Females will release eggs here
Asteroidea - sceptical tube foot
senses light
Asteroidea - dermal gill
releases CO2 and NH3, and takes up O2. Functions in gas exchange
Asteroidea - perivisceral coelom
completely enveloped in mesoderm, therefore, it’s a true coelom
Asteroidea - peritoneum
mesodermally derived and envelopes the internal organs. It’s like a sac
Asteroidea - digestive gland (pyloric cecum)
releases enzymes and absorbs nutrients from food
Feeding and digestion of each subgroup
- Echinoids: grazers, suspension feeders, selective deposit feeders
- Holothuroids: suspension feeders, selective deposit feeders, direct deposit feeders
- Ophiuroids: selective deposit feeders, predators
- Crinoids: suspension feeders
- Asteroids: predators, scavengers, detritus feeders, suspension feeders
Gas exchange of each subgroup
asteroids and echinoids use dermal gills
holothuroids use their respiratory tree
Ophiuroids use their bursae
