He Mich or Dates and Chord a Tesch

7/30/2019 He Mich or Dates and Chord a Tesch

1/31

Hemichordata and Invertebrate

Chordates


2/31

Phylum Hemichordata

Bilaterallysymmetrical.

Body divided into threesections, a proboscis, a collar

and a trunk.

Characteristics of Hemichordata:-

All live marine environments.


3/31

Body cavity a true

coelom divided into

three cavities.

Complete digestivetract, feeds on fineparticles in the water.

Dorsal, sometimestubular, nerve cord.


4/31

Class Enteropneusta

Burrow in sandy and

muddy substrates

Ciliated epidermis and glands

cover acorn worms

Marine worms

Common name acorn worms


5/31

Maintenance FunctionsVentral Mouth

Lateral Pharyngeal slits,few to several hundred

Cilia and mucus assist

acorn worms in feeding

Ciliary tracts convergenear the mouth and

form a mucoid string

that enters the mouth


6/31


7/31

Nervous system

Ectodermal in origin Lies at the base of

the ciliated epidermis

Consist of dorsal andventral nerve tracts

No major ganglia

Sensory receptorsare unspecialized


8/31

Respiration

Simple diffusion ofmetabolic waste

Cilia associated with

Pharyngeal slitscirculate water intomouth and out of body

Gas exchange aswater passes throughpharyngeal slits


9/31

Circulatory system

Colorless blood moves nutrientsand wastes

Dorsal and ventral contractilevessel

Blood moves anteriorly in dorsal

Posteriorly in ventral vessel

Branches from theses vessels

lead to open sinuses (Partially opencirculatory system)

Anterior flowing blood movesthrough glomerulus (excretory

organ)

Waste filtered into proboscis

coelom and out through pores


10/31


11/31

Evolutionary ties b/w hemichordatres

and echinoderms

Ciliated larvae


12/31

Class Pterobranchia

pteron- wing

branchia- gill

Deep marine water

Some live in shallow waters


13/31

Body divided

into threeregions

Size 0.1 - 5mm


14/31

Individuals

called

zooids


15/31


16/31

Maintenance Functions

Filter feeders

Cilia on tentacles trap and transport

Food to mouth

Respiration and excretory

exchange by diffusion


17/31

Reproduction and Development

Asexual budding is common and responsiblefor colony formation

Also some posses one or two gonads

Most species are dioecious

External fertilization

Planula-like larva (cnidarian)

Settles to a substrate, forms cocoon andmetamorphoses into an adult


18/31

Phylum Chordata

Characteristic of the chordates

Deuterostome embryo developmentNotochord, phayngeal slits or pouches,

dorsal tubular nerve cord, and postanal tailCoelomate animals

Bilateral symmetry

EndoskeletonTwo major groups: nonvertebrate chordates

and vertebrates


19/31


20/31


21/31


22/31

Body wall

Tunic- gown

Connective tissuelike covering

Tough secreted bythe epidermis

Composed ofproteins

Salts, cellulose Stolons extensions

of tunic help root


23/31


24/31


25/31


Monoecious

Self fertilization and cross fertilization


26/31

Subphylum Cephalochordata

Elongated laterally flattenednearly transparent

Lancelets

Size up to 5 cm tadpole likeanimals

All four chordatecharacteristics persist

throughout life Shallow waters

genera Branchiostoma(Amphioxus)


27/31


Dioecious

Gonads shed gametesinto the atrium

Leave the body throughthe atriopore

External fertilization

Bilaterally symmetrical

larva Larva free swimming

Larva Settle to substratethen metamorph into

adults


28/31

Maintenance Function

Filter feeders

Buried in sandy

substrate

Mouth pointed

upward


29/31

Cilia on lateral surfaces of gill sweep water into

mouth

Food sorted in the cirri

Edible particles move along cilia to the gut


30/31

No true heart

Contractile waves inthe walls of major

vessels propelblood

Blood contains

amoeboid cells andbathes tissues inopen spaces


31/31

Excretory tubules are modified coelomic

cells closely associated with blood vessels.

Coelom reduced- restricted to canals near the

gill bars endostyle and the gonads

Documents

He Mich or Dates and Chord a Tesch