Introduction to deuterostomes Flashcards
Deuterostomes
an animal whose anus is formed from the blastopore. mouth develops later
three major taxa (phyla)
Hemichordata
Echinodermata
Chordata
Name of common ancestor and charactetistics
Yunnanozoon
- bilaterally symmetrical
- segmentation
- pharynx with slits
Hemichordates
worm-like marine animals
- 3 part body plan (proboscis, collar, and trunk)
- burrow in mud or sand in marine habitats have pharyngeal slits
Pharyngeal slits
water enters mouth and exits via slits pharynx used for gas- exchange and respiration
Echinoderms
sea stars, sea cucumbers, sea urchins
- all marine
Characteristics of echinoderms
- pentaradial symmetry (adult)
- water vascular system
- tube feet, spines
- endoskeleton of calcareou ossicles
- bilaterally symmetrical when they are larvae
Binmpimaria
early stage of echinoderms
Brachiolaria
later larvae stage
branchy
The sister taxa of protostomes
deuterostomes
pentaradial symmetry
- unique to echinoderms
- body parts arranges radially in 5 or multiples of 5
water vascular system
- unique to echinoderms
- fluid filled canals and tube feet that function hydraulically for locomotion, feeding, and respiration
- water enters through madreporite
tube feet and spine
tube feet usually in grooves
-function in locomotion and feeding
spines: projections on surface that function in protection, give echinoderms their name
endoskeleton of calcareous ossicles
may be fused (sea urchins and sand dollars)
-may be dispersed ( sea cucumbers and sea stars)
Ophiuriods
- brittle stars
- move by bending 5 flexible, articulated arms (tube feet not used for locomotion)
- mostly suspension feeders, hold arms up to trap particles on sticky tube feet
Asteroids
- sea stars
- movie with tube feet
- all predators
- ecologically important
reproduction in sea stars
sexual -separates sexes, mostly broadcast spawn asexual - regenerative ability -can divide at central disc and regenerate missing have or regenerate a new individual from an arm -larvae can reproduce through budding
Echinoids
sea urchins
- move with tube feet that extend between spines
- large, movable spines for protection
- herbivores, feed on large algae
Holothuroids
sea cucumber/ sea pig
- move via rows of tube feet on ventral side
- suspension or deposit feeders; capture/collect particles with branching tube feet around the mouth
- eviscerate to escape predators
Crinoids
feather stars
- oldest group of living echinoderms
- sessile suspension feeders; catch particles on sticky tube feet extending from grooves on the “feathery” arms
Chordata
- all bilaterally symmetrical, coelomate and segmented
- monophyletic clade that includes vertebrates and 2 clades of invertebrates
4 key traits of chordates
- notochord
- pharyngeal slits
- dorsal, hollow nerve cord
- muscular, post-anal tail
notochord
flexible rod-like structure composed of large, fluid filled cells
dorsal, hollow nerve cord
spinal chord in humans
Muscular, post-anal tail
tail extends posterior to the anus
Cephalochordata
- invertebrate
- all marine, look like tiny transparent fish
- burrow in sediment with mouth sticking out
- suspension feedes- draw water into mouth and through pharyngeal slits
Urochordata
- invertebrate
- all marine, some sessile, others free-swimming
- solitary and colonial species with tadpole-like larval stage
- notochord, dorsal hollow nerve cord, and post anal tail ONLY in larval stage
3 clades of urochordata
ascidians
thaliaceans
larvaceans
Ascidians
sea squirts
- have secreted exoskeleton (tunic) of cellulose-like material
- have a brachial basket (perforated pharynx), water enters through oral siphon, food filtered to digestive system, waste ejected from atrial siphon
- tadpole larvae can swim, but adults are all sessile suspension feeders
Thaliaceans
salps
- like free-floating adult ascidians
- some are solitary, others form enormous colonies
- all are effective suspension feeders
Larvaceans
- like tadpole larvae (retain tail and notochord as adults)
- live in mucus house they contruct
- suspension feed by beating tail to pump water through house, food gets trapped in mucus, both food and mucus ingested
Vertebrata
synapomorphy is vertebrae
Characteristics of vertebrates
- jointed dorsal column
- anterior cranium (skull) with a large brain
- well developed circulatory system with a ventral heart
Agnathans
- hagfish and lamprey
- split off before evolution of jaws and mineralized skeleton
Gnathostomes
have jaws and bones
Hagfishes
- skeleton and cranium of cartilage
- no jaws, but tooth-like structures, made of protein, used to rasp tissue from dead organisms
- marine scavengers
- secrete tons of slime
Lampreys
- skeleton and cranium of cartiladge
- mostly parasites of fishes; attach and rasp at host tissue using tooth-like structures made of karatin
true or false:
hemichordate is a chordate
false
