Chaetognaths, Echinoderms, Hemichordates

phylum chaetognatha are the

arrow worms

phylum chaetognatha are have approximately (species and size)

70 species, 1-10 cm long

Phylum Chaetognatha are all

marine, free-living- planktonic

phylum chaetognatha symmetry

bilateral

phylum chaetognatha evolution

placement uncertain (embryonic development suggests deuterostome, DNA and adult suggest protostome)

Phylum Chaetognatha body

has 3 regions, head, trunk, tail

phylum chaetognathahas fins

lateral and caudal

phylum chaetognatha ganglia

circumesophogeal ganglia

phylum chaetognatha muscles

longitudinal muscles, no circular muscles

phylum chaetognatha does not have what systems

circulatory, excretory, or respiratory

phylum chaetognatha skeleton

hydrostatic skeleton

phylum chaetognatha reproduction

hermaphroditic; with cross-fertilization and internal fertilization

phylum chaetognatha feeding

carnivorous - predators of plankton

phylum echinodermata species

about 6,000 all marine

phylum echinodermata major characteristics (symmetry)

secondary pentamerous radial symmetry

phylum echinodermata major characteristics (skeleton)

internal skeleton

phylum echinodermata major characteristic system

water vascular system

water vascular system structures

madreporite, stone canal, ring canal, radial canal, lateral canals, ampullae, tube feet

water vascular system water goes in… and out….

madreporite, tube feet

classification of phylum echinodermata

crinoidea, asteroidea, ophiuroidea, echinoidea, holothuroidea

class crinoidea are the

sea lillies

class asteroidea are the

starfishes

class ophiuroidea are the

brittle stars

class echinoidea are the

sea urchins, sand dollars

class holothuroidea are the

sea cucumbers

class crinoidea most are

extinct

class crinoidea most

primitive

class crinoidea movement

sessile, with stalk that attaches to substrate

class crinoidea have

branched arms for filter feeding

class crinoidea have no

suckers on tube feet, madreporite, or pedicellariae

class asteroidea arms not sharply

delineated from central disc

class asteroidea tube feet

with suckers used for locomotion and obtaining food

class asteroidea have

madreporite and anus aborally located

class asteroidea some have

pedicellariae -jaw- like appendages of epidermis

class asteroidea feeding structures

mouth, cardiac stomach (can be extruded), pyloric stomach, pyloric caecae, anus

class asteroidea feed primarily on

sessile organisms

class asteroidea systems

circulation, excretion, respiration, nervous

class asteroidea circulation

poorly developed with fluid filled chambers; no heart; coelom ciliated for fluid movement

class asteroidea excretion

no special organs, general diffusion across body surfaces like tube feet

class asteroidea respiration

no special organs, across body membranes (tube feet, dermal branchiae)

class asteroidea nervous system

associated with epidermis, circular oral nerve ring with branches into arms

class asteroidea body wall

epidermis, dermis, muscle layer, peritoneum

class asteroidea epidermis

outer surface includes: mucous cells, epithelium, pedicellariae jaw like appendages of the epidermis

the pedicellariae can

open and close and is used to clean body of debris or put debris on body

class asteroidea dermis includes

nerve cells, connective tissue, skeleton

class asteroidea skeleton

made of ossicles, lattice like connections, with spines and tubercles

class asteroidea muscle layer

below dermis

class asteroidea peritoneum

lines coelom

class asteroidea reproduction

mostly dioecious with external fertilization although many will participate in pseudocopulation

class asteroidea gonads

usually 10, 2 in each arm

class asteroidea reproduction, have

fissiparity- division of central disc into two animals

class asteroidea reproduction larvae

free living larvae

class asteroidea the free living larvae are

bipinnaria and brachiolaria

bipinnaria is the

first larval for of class asteroidea and develops into brachiolaria

brachiolaria is the

second form of larvae in class asteroidea that shows development of arms

class asteroidea a few brood larvae with

parental care (monecious species)

class ophiuroidea usually have

5 arms

class ophiurodea have a

central disc well marked off, no branches of gut in arms

class ophiuroidea do not have

an anus, ambulacral groove, suckers on tube feed, ampullae (have a valve to control pressure), or pedicellariae

class ophiuroidea madreporite on

oral surface

class echinoidea have no

arms

class echinoidea skeleton

is fused into a solid test

class echinoidea tube feet have

suckers

class echinoidea covered with

moveable spines and pedicellariae

class echinoidea specialized mouth structures

aristotle’s lantern

class holothuroidea body

elongated in oral-aboral axis

class holothuroidea skeletal system

reduced or absent

class holothuroidea no

spines or pedicellariae

class holothuroidea mouth and anus

at opposite ends of body

class holothuroidea no external

madreporite

class holothuroidea tube feet

with suckers

class holothuroidea respiration through

anal respiratory tree

class holothuroidea reproduction

dioecious; single gonad

class holothuroidea feeders

suspension or detritus

class holothuroidea commensal relationship with

pearl fish

class holothuroidea some expel

their guts as a defense mechanism

phylum hemichordata formally was a subphylum under… based on having

chordates, gill slits, rudimentary notochord (but is a buccal diverticulum)(blindly ending pouch of the gut that reaches the buccal region), stomochord (mouth cord), not homogous with chordate notochord

phylum hemichordata have a

dorsal and ventral nerve cord

phylum hemichordata are

deuterostomata

phylum hemichordata species

about 100 species, all marine, .5cm-2m

phylum hemichordata live

benthic (live on the bottom) and free living

phylum hemichordata are

solitary or colonial

phylum hemichordata can

vermiform - elongate

phylum hemichordata body in

3 parts; proboscis, collar, and trunk

phylum hemichordata respiration

gill slits

phylum hemichordata do not have

post-anal tails

phylum hemichordata larvae

free living called tornaria

phylum hemichordata resemble

echinoderm larvae

phylum hemichordata primarily feeding on

detritus and microscopic organisms

phylum hemichordata have what system

circulatory system; two main blood vessels and a central sinus (heart)

phylum hemichordata sexes

are separate; fertilization is external