Proteosome animals

3 base Traits of protosomes

Triploblastic, Mouth develops first, Bilateral symmetry

2 derived traits

• anterior brain that surrounds the entrance to the digestive tract

• ventral nervous system with paired or fused longitudinal nerve cord

2 Major sections

Lophotrochozoan and Ecdysozoans

Lophotrochozoan get their name from?

name gotten from having a trochophore larva and a lophophore

Lophophore tentacle features

Circular or U-shaped ring of hollow, ciliated tentacles around the mouth; functions in food collection

Ecdysozoans cuticle

have an external cuticle, secreted by the epidermis

• cuticle protects and supports

• once formed the cuticle cannot grow

• they shed or molt cuticles to replace small cuticle with a larger one (ecdysis)

Trade off for cuticle exoskeleton

exoskeleton restricts movement and gas exchange

• appendages manipulated by muscles evolved in the arthropod clade

• arthropod appendages are also used for food capture gas exchange copulation and sensory perception

• the hard exoskeleton allowed for walking on dry land and prevent drying

Arrow worms

Genes say it is a Proteosome. Blastopore gives rise to anal opening, they have ventral nerve cord and spiral cleavage

- Not listed at either Lophotrochozoan or Ecdysozoans

- transparent - head, trunk, and tail

- most swim in the open sea; other live on the sea floor

- small-gas exchange and waste excretion occurs by diffusion

- no circulatory system: wastes and nutrients are moved by cilia that line the coelom

- no larval stage: miniature adults hatch from eggs that are fertilized internally following elaborate courtship.

- a major predator of plankton

- hermaphroditic

Hermaphroditic

each individual produces both mala and female gametes

Lophotrochozoan

Bryozoans, Entroprocts, Flatworms, Rotifers, Ribbon worms, Brachiopods, Annelids, Mollusks

Ecdysozoans

Nematodes, Tardigrades , Velvet worms​, Arthropods