The Lesser ProtostomesThe Lesser Protostomes

The Lesser ProtostomesThe Lesser Protostomes

• Phyla contain few numbers of species Phyla contain few numbers of species

• All phyla are aquatic organismsAll phyla are aquatic organisms

• Recorded in the fossil record – especially Recorded in the fossil record – especially fossil beds such as the Burgess shalefossil beds such as the Burgess shale

• Morphologies are intermediate to the Morphologies are intermediate to the morphologies of the major lophotrochozoa morphologies of the major lophotrochozoa phyla Mollusca, Annelida and the Ecdyzoa phyla Mollusca, Annelida and the Ecdyzoa phylum Arthropodaphylum Arthropoda

Lessor Lophotrochozoan PhylaLessor Lophotrochozoan Phyla

Phylum GnathostomulidaPhylum Gnathostomulida• 11stst discovered discovered

1928, formally 1928, formally described 1956described 1956

• 18 genera, 80 18 genera, 80 speciesspecies

• 0.5-1mm0.5-1mm

• Feed on bacteria, Feed on bacteria, fungal, & fungal, & protozoan cells in protozoan cells in sedimentsediment

• AceolomicAceolomic

• Incomplete Incomplete digestive tractdigestive tract

• Monociliated Monociliated epidermal cellsepidermal cells

Gnathostomula jenneri

Gnathostomula paradoxa

Phylum MicrognathozoaPhylum Micrognathozoa

Phylum MicrognathozoaPhylum Micrognathozoa

• 1 species !!!1 species !!!

• 11stst discovered 1994, formally described 2000 discovered 1994, formally described 2000

• 0.1-0.2mm0.1-0.2mm

• Complete gutComplete gut

• Complex jawComplex jaw

• Only females found Only females found – Parthenogenetic ? Parthenogenetic ?

Phylum RotiferaPhylum Rotifera• ~2000 species~2000 species

• Corona of ciliated Corona of ciliated cellscells

• PseudoceolomicPseudoceolomic

• Central nervous Central nervous systemsystem

• Complete gutComplete gut

• Many species are Many species are female onlyfemale only– Parthenogenetic Parthenogenetic

Phylum RotiferaPhylum Rotifera

• Rotifer YouTube MovieRotifer YouTube Movie

Parthenogenetic ReproductionParthenogenetic Reproduction

•Females are diploidFemales are diploid– Amictic eggsAmictic eggs

•Produced by mitosisProduced by mitosis

•Are not fertilizedAre not fertilized

– Mictic eggsMictic eggs•Produced by meiosisProduced by meiosis

•Develop w/o fertilization into haploid maleDevelop w/o fertilization into haploid male

•Fertilized mictic eggs enter dormancyFertilized mictic eggs enter dormancy

Phylum AcanthocephalaPhylum Acanthocephala

Phylum GastrotrichaPhylum Gastrotricha

• ~500 species~500 species

• 0.06-0.5mm0.06-0.5mm

• Feed on bacteria Feed on bacteria & protozoa& protozoa

• HermaphroditicHermaphroditic

• Freshwater Freshwater species species parthenogeneticparthenogenetic

Chaetonotus simrothi

Phylum CycliophoraPhylum Cycliophora

• Discovered 1995Discovered 1995

• 0.35-.1mm0.35-.1mm

• Live on mouthparts of marine decapod crustaceansLive on mouthparts of marine decapod crustaceans

Simbion pandora

Phylum PhoronidaPhylum Phoronida

Phoronis hippocrepia

Phoronopsis viridis

Phylum Phylum EctoproctaEctoprocta (Bryozoa) (Bryozoa)

Electra pilosa

Plumatella repens

Bryozoan MicrographsBryozoan Micrographs

Ectoprocts Ectoprocts (Bryozoans)(Bryozoans)

Bugula sp

Phylum Phylum BrachiopodaBrachiopoda

Phylum BrachiopodaPhylum Brachiopoda