Lophophorates and Deuterostomes

The three Lophophorate phyla

Bryozoa

Phoronida

Brachiopoda

The three Deuterostome phyla

Echinodermata

Hemichordata

Chordata

Lophophorates

Food-catching tentacular organs - called

lophophore

All are/have

Sessile

Poorly developed head

Secrete a protective covering

u-shaped digestive tract

Bryozoa

5000 species

Minute <0.5mm - no internal transport system

Colonial - polymorphic - different zooids have different function

Planktonic larval stage

Hermaphrodites

organisms that contain both female and male sex organs.

Bryozoan zooids anatomy

Surrounded by a wall if chitin - some are calcified

Mouth within funnel of tentacles

Anus outside of tentacles

Extrude lophophore by increase in pressure in the coelom and withdrawn by retractor muscles

Hornwarck latin name

Flustra foliacea

Phoronida phylum

14 species

live in chitinous tubes buried in sand

less than 20cm long

worm-like

Brachiopoda phylum

325 species

two valves - dorso-ventral

Attached to rock by pedicel - fleshy stalk

Lophophore within valves which gape open for water current flow

Echinodermata phylum

6000 species

Starfish, brittle stars, sea urchins, sea cucumbers and sea lilies

Echinoderms physiology

pentamerous radial symmetry

larvae are bilateral

show secondary radial symmetry - evolved from bilateral ancestor

benthic

water vasculatory system

What is the endoskeleton of echinoderms made of?

Calcareous ossicles

Water vascular system of echinoderms

Opens to exterior vis the madreporite - fluid is similar to sea water but more potassium ions, proteins and cells

Sea cucumber class

Holothuroidea

detritivores

small ossicles

Sea urchin and sand dollar class

Echinoidea

Spherical or Dorsoventrally flattened

Body - 5 ambulacral plates

5 interambulacral plates

Aristotles lantern

mouth-like apparatus in sea urchins

Function of pedicellaria in sea urchins

cleaning and defence

Sea lily and feather star class

Crinoidea

Flexible pinnules (arms)

sessile - ancestral echinoderm

Sea stars and brittle stars class

Stellaroidea

Sea star subclass

Asteroidea

1600 species

Mouth on ventral surface

Can regenerate arms if disturbed or attacked

Brittle star sub-class

Ophiuroidea

2100 species

Two main hemichordate classes

Enteropneusta (acorn worms)

Pterobranchia/Planctosphaeroidea

3 chordata sub-phyla

Tunicata - invertebrates

Cephalochordata - invertebrates

Vertebrata - vertebrates

Features of a chordate

Notochord

Visceral clefts in pharynx

CNS hollow, dorsal and tubular

Heart ventral

Post-anal, metamerically segmented tail

Features of a non-chordate

CNS ventral, solid and double

Heart dorsal

Absent post-anal tail

What is a notochord

Tough flexible rod that muscles may attach to - replaced by the vertebral column

What is a visceral cleft?

paired openings leading from the pharynx to the ectoderm

Tunicata classes

Ascidiacea - sea squirts Appendicularia - Larvaceans

Thaliacea - salps

Sordberacea - abyssal ascidian like forms

Ascidiacea Life cycle

Fertilised egg - tadpole - sessile adult (radical metamorphosis)

Ascidiacea forms

solitary and colonial

Rhopalaea/Didemnum

botrylloides leachii

Appendicularia life cycle

fertilised egg - tadpole larvae - adult retains larval characteristics but is sexually mature

Cephalochrodata

fish-like animals called Lancelets - filter feeding

Vertebrata characteristics

Cranium - protects brain

Vertebral column (bone/cartilage)

Highly developed tripartite brain

Development of neural crest