Deuterostomes PART ONE

when did prokaryotes first appear?

in the archean eon, around 3500 mya

when did eukaryotes first appear?

in the proterozoic eon, around 2100,1004 mya

when did multicellular soft-bodied animals first appear?

in the proterzoic eon, around 600 mya

what was the archean eon like?

very litttle oxygen

what was the early proterozoic period like?

start of the ‘oxygen crisis’ - cyanobacteria started producing oxygen and the atmosphere starts oxidising

what was the mid-proterozic eon like?

the ‘boring billion’

what was the late-proterozoic period like?

introduction of the first animals, oxygen fills the atmosphere as the ocean had absorbed as much as it could

what was the phaneozic eon like?

introduction of land plants as well as larger, more diverse and disparate animals

what was introduced in the jurassic period?

modern sharks, rays, first birds, lizards

what was introduced in the triassic period?

reptile radiation, first mammals and teleost fish

what was introduced in the permian period

amniote radiation, mammal-like reptiles

what was introduced in the carboniferous period?

fish diversification, first bony fish, first amniotes

what was introduced in the devonian period?

‘age of the fishes’, multiple radiations, first tetrapods

what was introduced in the silurian period?

jawless fish radiation, first sharks

what was introduced in the ordovician period?

jawless fish, land plans

what was introduced in the cambrian period?

complex invertebrates

what percentage of described species are invertebrates?

96%

what does protostome mean?

‘first mouth’

what does deuterostome mean?

‘second mouth’

key development of protostomes?

spiral and determinate cleavage, blastopore becomes the mouth, schizocoelous coelom formation (mesoderm split)

key development of deuterostomes

radial and indeterminate cleavage, blastopore becomes the anus, enterocoelous coelom formation (gut outpocketing)

cleavge pattern types

holoblastic, meroblastic, equal, unequal

type of cleavage?

determinate cleavage, where developmental fate is established early

type of cleavage?

indeterminate cleavagewhere early embryonic cells retain capacity to develop into complete embryo (if isolated)

what does the cleavage produce?

blastula

types of blastula?

coeloblastula (hollow), stereoblastula (solid), discoblastula (cell cap above yolk), periblastula (cell layer enclose yolk)

three germ layers of triploblastic animals?

ectoderm, mesoderm, endoderm

what generates the three germ layers of triploblastic animals?

gastrulation

what is gastrulation?

early embryonic process where a blastula reorganises into a three-layered structure (gastrula) with distinct tissue layers

when did deuterostomes first appear?

beyween the ediacaran to cryogenian period, around 660-570 mya

major lineages of deuterostomes?

chordata and xenambulacraria

whats found in the chordata lineage?

tunicates, cephalochordates, vertebrates

whats found in the xenambulacraria lineage?

hemichordates (‘half-chordates’), echinoderms, (xenacoelomorphs?)

what are xenacoelomorpha a phlyum of?

small marine worms

two major lineages of phylum hemichordates?

enteropneusts (around 110sps), pterobranchs (around 25sps)

what are enteropneusts?

solitary, elongate, vermiform animals whose body divides into 3 regions

body regions of enteropneusts?

proboscis, collar, trunk

enterophneusts core physiological processes

open circ, dorsal nerve, gill slits, complete digest sys

enteropneusts feeding technique?

burrowers, filter or suspension feeders

what are pterobranchs?

colonial, tube dwellers with a share tripartite body plan, gill slits and stomochord (shared: enteropneusts)

pterobranchs feeding tehcnique?

feeding arms with tentacles

pterobranch reproduction stratergies?

distinct male/female, but can also reproduce asexually (budding)

hemichordates ecological roles?

nutrient cycling, bioturbation, habitat structuring

benefits of hemichordates helping with bioturbation?

burrows (of burrowing sps) improve oxygenation, nutrient exchange, microbial activity

benefits of hemichordates helping with habitat structuring?

tubes provide habitat, attachment points, shelter for other species

what are planctosphaera?

occasionally found larvae with unknown adult form that could potentially be a distinct hemichordate lineage

what are the major lineages of echinoderms (over 7000 sps)?

asteroidea, ophiuroidea, holothuroidea, echinoidea, crinoidea

what organisms are found in asteroidea?

sea stars, star fish

what organisms are found in ophiuroidea?

brittle stars

what organisms are found in holothuroidea?

sea cucumbers

what organisms are found in echinoidea?

sea urchins, sand dollars

what organisms are found in crinoidea?

sea lillies, feather stars

symmetry found in echinoderms?

radial sym in adults and bilat sym in larvae, gen pentamerous (split into five)

echinoderm skeleton strcuture

calcareous endoskeleton with ossicles (plates) and tubercles (spines)

what system is this?

the echinoderms water vascular system?

what is the function of the madreporite?

filters water into the water vascular system

what is the function of the stone canal?

connect the madreporite with the water vascular system

what is the function of the ring canal?

circular water tube that surround the esophagus

what is the function of the radial canal?

ciliated canal in the arm

what is the function of the ampullae?

prevents water from flowing back to the radial canal

what is the function of the tube feet

used for movement