Chapter #33- Lophotrochozoans

Bilaterian animals have

bilateral symmetry

bilateria contains 3 super phyla

lophotrochozoa, excdysozoa, deuterostomia

Lophotrochozoans include

platyhelmithes, mollusca, annelida

Phylum- Playhelminthes

flatworms that are acoelomates and are flattened dorsoventrally, gas exchange takes place across the surface

4 classes of flatworms

turbellaria, monogenea, trematoda, cestoda

Class- Turbellarians

free-living and marine animals

most common turbellarian

Planarians- they have light-sensitive eyespots and can regenerate lost body parts

Monogeneans and Trematodes

parasites of vertebrates that lack a digestive system, they absorb nutrients from their hosts

Proglottids

contain fertilized eggs that leave the host’s body in feces

Phylum Mollusca includes

snails, slugs, oysters, clams, octopuses, and squids

3 main parts that molluscs have

muscular foot, visceral (guts) mass, mantle

mantle cavity with radula

molluscs have a water filled cavity and feed using the rasplike radula

4 main classes of molluscs

polyplacophora, gastropoda, bivalvia, cephalopoda

Class Polyplacophora

consists of chitons- oval-shaped marine animals encased in an armour of 8 dorsal plates

Class Gastropods

marine and freshwater species like snails and slugs, most have a single spiraled shell

Class Bivalvia

includes clams, oysters, mussels, and scallops, have a shell divided in 2 halves, contal gills that are used for feeding and gas exchange

Class Cephalopoda

includes squids, octopus, and nautilus with beak-like jaws surround by tentacles of their modified foot

Cephalopodas have

well-developed sense of organs and a complex brain

Phylum Annelida

have bodies composed of a series of fused rings

main class of Annelida

clitellata

2 sub-classes of Clitellata

oligochaeta, hirudinea

Subclass Oligochaetes

named for chaetae- bristles made of chitin

example of an oligochaetes

eathworms who are conveyor belt feeders that extract nutrients through their alimentary canal

Subclass Hirudinea

blood sucking parasites like leeches

Hirudin

chemical that leeches secrete to prevent blood from coagulating