Basal Deuterostomes Flashcards
traits common to all Deuterostomes
blastopore becomes anus, have a true coelom
4 key Deuterostome Phyla
Chaetognatha, Echinodermata, Hemichordata, and Chordata
Phylum known as arrow worms
Phylum Chaetognatha
characters of Phylum Chaetognatha
small pelagic predators, don’t exactly know where they fit in the tree of life
method of feeding for Chaetognaths
spines around the mouth grab onto prey
Phylum of Deuterostoma containing Enteropneusta and Pterobranchia
Phylum Hemichordata
general characters of Phylum Hemichordata
aquatic, separate sexes, external fertilization, tornia larva
similarities between Phylum Hemichordata and Phylum Chordata
gill slits in the pharynx, some have a hollow neural tube
tornia larva
characteristic of Hemichordates, swim with a ring of cilia on base and track of cilia along the body
two key classes of Phylum Hemichordata
Enteropneusta and Pterobranchia
class of Phylum Hemichordata known as acorn worms
Class Enteropneusta
characters of class Enteropneusta
solitary animals living in u-shaped burrows with large casts of feces on one end
method of feeding for class Enteropneusta
proboscis acts to open/close mouth and cilia on proboscis move food particles into mouth when open
tagmata of class Enteropneusta
proboscis, collar, and trunk
class of Pylum Hemichordata known as pterobranchs
class Pterobranchia
characters of class Pterobranchia
live colonially in self-secreted tubes
method of feeding for class Pterobranchia
ciliated tentacles collect food from water column
tagmata of class Pterobranchia
proboscis, collar, and trunk
Phylum of Deuterostoma containing sea stars, brittle stars, sea urchins, and sea cucumbers
Phylum Echinodermata
general characters of Phylum Echinodermata
entirely marine, adults are commonly pentaradial (with bilateral larva), generally rough and spiny
tiny pinchers around Echinoderm spines used for parasite removal
pedicellariae
valve on aboral side of Echinoderms used for regulating water movement
madreporite
structure of Echinoderms
five ambulacral areas on the oral side each containing tube feet
two coelomic cavities present in Echinoderms
somatocoel and water-vascular system
somatocoel
coelomic cavity in Echinoderms housing organs
water-vascular system
hydraulic system of tubes and tube feet present in Echinoderms used for feeding, respiration, and locomotion
process of water-vascular system
water enters via the madreporite and goes through the stone canal to the ring canal, then out to radial canals and the ampullae/tube feet
nervous system of Echinoderms
nerve ring, sometimes have tentacles or eyespots
circulatory system of Echinoderms
none
structure of Echinoderm exoskeleton
ossicles fused together in various ways create the exoskeleton
reproduction of Echinoderms
distinct sexes are generally not dimorphic, external fertilization
key classes of Echinodermata
Asteroidea, Ophiuroidea, Echinoidea, and Holothuroidea
class of Echinodermata known as sea stars
class Asteroidea
characters of Asteroidea
found from intertidal zone to abyss, typically have all general characters of Echinoderms (5 arms, madreporite, tube feet), can regenerate limbs
two stomachs found in Asteroideans
pyloric stomach and cardiac stomach
purpose of cardiac stomach in Asteroideans
everted during feeding, begins digestion outside of the body
purpose of pyloric stomach in Asteroideans
connects consumed food to pyloric cecae in arms where digestion can be completed
purpose of pyloric cecae in Asteroideans
one in each arm, act as intestines
class of Echinodermata known as brittle stars and basket stars
class Ophiuroidea
characters of brittle stars
FUCKING HORRIBLE, madreporite on oral side, ambulacral grooves covered over with hard plates, tube feet have no suckers, no anus or intestines, no organs in the arms, mouth made from five jointed plates
characters of basket stars
also just terrible, “fans” are branches of the five legs, live in the tropics
class of Echinodermata known as sea urchins and sand dollars
class Echinoidea
characters of class Echinoidea
ossicles fused to form a test, ambulacral grooves extend all the way to aboral pore (oral side covers whole body), huge reproductive organs
locomotion in Echinoideans
sae urchins use both tube feet and spines to move, sand dollars use only spines
feeding methods for Echinoideans
mouthpart called Aristotle’s Lantern scrapes ocean floor (some Echinoideans can also filter feed)
class of Echinodermata known as sea cucumbers
class Holothuroidea
characters of class Holothuroidea
elongated body, reduced ossicles, no spines of pedicellariae, five rows of tube feet
locomotion in class Holothuroidea
can move with tube feet or via muscular contractions
location of madreporite in Holothuroideans
inside the pharynx
respiration and excretion in Holothuroideans
cloaca pumps water in and out of the respiratory tree to allow gas exchange between the body cavity and the water column
