Animal Diversity 6: Lophotrochozoans

What characters define Lophotrochozoa

• Distinct organ systems

• Bilateral symmetry along an anterior-posterior axis; three embryonic cell layers; centralised nervous system

• Protostomes

• Blastopore develops into mouth

Describe Lophotrochozoan phylogeny

• Incredibly diverse clade

• ~ 13 phyla

• No common morphological trait across all groups

• Monophyletic

• Internal resolution controversial

What are the lophophore and trochophore

Lophophore – feeding structure

Trochophore – larval morphology

Describe Bryozoa (Ectoprocta)

• 5,500 species

• colonial

• clones of one another

• division of labour

• lophophore

• well developed gut

• marine filter feeders largely

Describe Entoprocta

• superficially similar to ectoprocta

• goblet animals or nodders

• attached to substrate

• colonial

Describe Cycliophora

• tiny

• only found on bristles of mouth of Norwegian lobsters

• 0.04 - 0.06mm

• three species

Describe Gnathifera

• clade of three phyla (Gnathostomulida, Micrognathozoa, Rotifera)

• synapomorphy mastax

• chewing structure

Describe Rotifera

• ‘Wheely animals’

• thorny headed worms

• filter feeders and parasites

• 3k species

• corona of cilia

Describe Micrognathozoa

• ‘Jaw animals’

• one species

• only females found

• asexual maybe

• two kinds of eggs

• slow and fast hatching,

Describe Gnathostomulida

• ‘Jaw worms’

• abundant in marine sediments

• hermaphrodites

• no body cavity

• circulatory or respiratory system

Describe Gastrotricha (new clade)

• ‘Hairybacks’

• water dwelling worms usually >1mm

• can be visible to the naked eye

• 800 species described

Describe Platyhelminthes

• Flatworms

• flukes and tapeworms

• have lost many ancestral features

• all soft bodiedsoft-bodied

• some terrestrial forms in tropical regions

• many parasitic types

• flatworms likely ancestral group

• some predatory species

Describe Brachiopoda

• ‘Lamp shells’

• lophophore

• superficially bivalve like

• filter feeders

• 300 species

• used to be more diverse pre-Permian extinction

Describe Phoronida

• Horseshoe worms

• sessile marine life

• some bore holes into rocks

• originate in Devonian

Describe Nemertea

• Ribbon worms

• don’t have any segmentation

• longest animals on the planet

• largely marine

• largely predatory

Describe Annelida

• Segmented worms

• symmetrical

• two major groups: Clitellates, Polychaetes

Describe Clitellates

• Leeches

• highly diverse

• meteramisme

Describe Polychaetes

• Named after bristles

• parapodyia

• extremely diverse

• exclusively marine

Describe the ecological importance of an annelid e.g. earth worm

• fertilisation

• aeration

• drainage

• prevent compaction

Mollusca is second only to which clade in diversity

Second only in diversity to arthropods in diversity

Describe Gastropods and their feeding apparatus

Gastropods:

• mostly herbivores, some carnivores such as sea angels

• they have a planktonic larva post trochophore stage

• snails, slugs, sea angels, nudibranch

Gastropod feeding apparatus:

• radula – toothed, chitinous

• odontophore – cartilaginous

• buccal mass – protractor and retractor muscles

• radula tooth, has been modified into predatory uses in some species

 

Describe Cephalopods

• Largely predatory

• mimicry

• highly intelligent