Download How do Echinoderms feed and digest?

How do Echinoderms feed and digest?
Crinoids
Filter feed with oral side up and arms and pinnules outstretched.
Food particles brought to mouth via cilia in ambulacral grooves.
Mouth opens to short esophagus, to
long intestine, to anus.
How do Echinoderms feed and digest?
Asteroids
Most are predators and scavengers. Eversible portion of stomach
(cardiac stomach) extruded onto or into prey.
How do Echinoderms feed and digest?
Asteroids
Mouth ---> cardiac stomach ---> pyloric stomach ---> pyloric ducts
---> pyloric cecae ---> intestine ---> anus
How do Echinoderms feed and digest?
Ophiuroids
Predators, scavengers, filter feeders, deposit feeders.
Food collected and passed along podia and spines to mouth.
Digestive system reduced with no anus.
How do Echinoderms feed and digest?
Echinoids
Herbivores, suspension feeders, detritovores.
Urchins have Aristotle’s lantern. Hard plates and muscles that
control protraction of five teeth.
Teeth scrape algae off rocks and take
bites of macroalgae. Can excavate
holes in rocks.
How do Echinoderms feed and digest?
Echinoids
Digestive mouth system ---> esophagus out of Aristotle’s lantern --->
long intestines ---> rectum ---> anus.
How do Echinoderms feed and digest?
Holothuroids
Suspension and deposit feeders.
Extend mucus-covered buccal tentacles into water. Tentacles are
pushed into mouth one at a time.
Mouth ---> esophagus ---> long intestines ---> rectum ---> anus.
How do Echinoderms feed and digest?
Holothuroids - defense against predators
Cuverian tubules -sticky tubes at base of respiratory tree. Entangle
predators.
Evisceration – discharge of all or part of the digestive organs
Organs are regenerated later
How do Echinoderms maintain homeostasis?
Circulation
Internal transport by coeloms, water vascular system, and hemal
systems.
Hemal system -array of canals and spaces enclosed within coelomic
channels called perihemal sinuses. Parallels water vascular system.
Probably helps distribute respiratory gases and nutrients.
How do Echinoderms maintain homeostasis?
Gas exchange
Across podia and dermal gills (dermal
branchia).
Countercurrent exchange.
How do Echinoderms maintain homeostasis?
Gas exchange
Ophiuroids have ten invaginations in the
body wall called bursae. Water circulated
by cilia.
How do Echinoderms maintain homeostasis?
Gas exchange
Holothuroids have respiratory trees. Water is actively pumped
by muscular hind end. Gases picked up by coelom and
hemal system.
How do Echinoderms maintain homeostasis?
Osmoregulation
Osmoconformers.
Waste is usually ammonia lost across podia and dermal
branchia.
How do Echinoderms reproduce and develop?
Asexual reproduction
Most capable of regenerating lost parts. Holothuroids
regenerate intestines and respiratory trees.
Asteroids and ophiuroids regenerate lost arms and suckers.
How do Echinoderms reproduce and develop?
Sexual reproduction
Most gonochoristic.
Gonads housed in genital sinuses. In classes with multiple
gonads, each has own gonopore in an interambulacral area.
How do Echinoderms reproduce and develop?
Sexual reproduction
Free spawning with indirect development to brooding with
direct development.
How do Echinoderms reproduce and develop?
Sexual reproduction
Isolecithal egg with small amount of yolk.
Radial holoblastic cleavage ---> coeloblastula --->
coelogastrula by invagination ---> blastopore becomes anus
---> coelom formation by enterocoely ---> embryo becomes
bilaterally symmetrical and develops into a larva.
Vitellaria of crinoid
Bipinnaria and brachiolaria of seastars
How do Echinoderms reproduce and develop?
Sexual reproduction
Isolecithal egg with small amount of yolk.
Radial holoblastic cleavage ---> coeloblastula --->
coelogastrula by invagination ---> blastopore becomes anus
---> coelom formation by enterocoely ---> embryo becomes
bilaterally symmetrical and develops into a larva.
Ophiopluteus of
brittle star
Echinopluteus
of urchin.
Aricularia of
sea cucumber