Invertebrates - Lophotrochozoa

Lophotrochozoa

mollusca, annelida, platyhelminthes

Platyhelminthes habitats

marine (Turbellarians), freshwater, and damp terrestrial habitats

Parasitic flatworms

trematodes (flukes) and tapeworms

Platyhelminthes body type

dorsoventrally flattened acoelomates

Gastrovascular cavity _____

branches throughout the body

Advantage of flat body

increases surface area (respiration through diffusion across body surface)

Planarians

free-living flatworms that live in freshwater and prey or feed on smaller or dead animals

Function of eyespots

light-sensing in order to move away from light (lives under rocks)

Planarian nervous system

centralized and more complex than that of cnidarians

Planarian reproduction

hermaphrodites but some reproduce by fission

Trematodes

diverse hosts and complex life cycles with alternating sexual and asexual stages (many require an intermediate host where larvae develop)

Tapeworms

parasites of mostly vertebrates that absorb nutrients directly from the host’s intestine

Scolex

anterior end of tapeworm, contains suckers and hooks for attaching to host

Proglottids

units that contain sex organs and form a ribbon behind the scolec

Tapeworm reproduction

after sexual reproduction, proglottids carrying thousands of eggs leave the host’s body in feces

Phylum Mollusca includes the major clades ______

gastropods, bivalves, cephalopods

Mollusc body type

have a coelom and hemocoel

Mollusc reproduction

many have separate sexes but some are hermaphrodites

Mollusc body plan (4)

muscular foot, visceral mass, mantle, radula (lost or modified)

Muscular foot

usually used for movement

Visceral mass

containing most of the internal organs

Mantle

a fold of tissue draping over the visceral mass that secretes the shell

Radula

strap-like, scrapes up food

Gastropods

snails and slugs

Gastropod habitats

most are marine, but also freshwater and terrestrial species

Terrestrial snails lack gills and use ______

the lining of the mantle cavity for gas exchange with the air

Gastropod feeding

most are herbivores but some species use modified radula to feed on prey

Bivalves

oysters, clams, mussels, etc.

Bivalve habitat

all aquatic (marine and freshwater)

Bivalve feeding

suspension feeders with incurrent siphon and excurrent siphon

Cephalopods

squids, octopuses, nautiluses, cuttlefish

Cephalopod feeding

active marine predators with beak-like jaws surrounded by tentacles and immobilize prey using a poison in their saliva

Cephalopod modified foot

modified into a muscular excurrent siphon and part of the arms and tentacles

Cephalopod nervous system

well-developed sense organs and a complex brain

T/F - Octopuses and Squids can release ink

True

T/F - Only octopuses have muscle controlled Chromatophores

False

Squid appendages

8 arms and 2 longer tentacles with toothed or hooked suckers

Octopus appendages

8 arms

Annelids

segmented worms that live in marine, freshwater, and damp soil habitats

Annelid body type

coelom and no hemocoel

Annelid clades

Errantia and Sedentaria

Errantia

large and diverse, mostly marine

Errantia mobility

mobile swimmers, crawlers, or burrowers with a pair of paddle (or ridge-like) parapodia on each body segment

Parapodia

used for locomotion and gills in many species — each parapodium has numerous chaetae (bristles made of chitin)

Sedentaria

less mobile than Errantians and include many tube-dwelling worms like feather dusters (earthworms and leeches)

Leeches

mostly freshwater (some terrestrial) — predators of invertebrates and some parasites of vertebrates

Earthworms

eat through soil, extracting nutrients and eliminating undigested material as fecal casting — hermaphrodites that cross-fertilize by joining in opposite directions to exchange sperm