Chapter 28 Invertebrates

includes mollusks arthropods, cnidarians, porifera, development and structures

Parapodia

are two sided or  paired structures on each body segment of annelids and are paddle shaped

Metazoa

All animals

Eumetazoa

Animals with true tissues

Radial

Symtry around central axis

Bilateral

Right and left mirror symmetry

Protostome

mouth develops first

Deuterostome

anus develops first

Ammonites

Extinct spiral shelled cephalopods

Ecdysis

Shedding exoskeleton

Spongocoel

central cavity of a sponge

Osculum

opening where water exits a sponge

Choanocytes

Collar cells that capture food

Amoebocytes

Mobile cells distributing nutrients

Hermaphrodites

Organisms with both sex organs

Cnidrarians

Jellyfish, corals and anemones

polyp/medusa

Sessile form/ free swimming form

Cnidocytes

stinging cells

Nematocysts

Harpoon like stinging structures

Coelom

mesoderm lined body cavity

Pseudocoelom

Body cavity not fully lined by mesoderm

Lophophore

feeding structures with tentacles

Ecdysozoa

Protostomes that molt (ecdysis)

Deuterostomia 

Group including chordates and echinoderms

Echinoderms

include starfish sea urchin and sea cucumber

Parthenogenesis

reproduction from unfertilized eggs

muscular foot

movement structure in mollusks

Visceral mass

contains internal organs

mantle

tissue that forms on the shell

radula

scraping feeding tongue

Cuticle

external covering/ exoskeleton layer

chitin 

tough polysaccharide in exoskeletons 

chelicerae

claw like feeding appendages

Arachnids

spiders, scorpions, ticks, mites

Hirudin

Anticoagulant from leaches 

open circulatory system

blood not always in vessels

book lungs

stacked respiratory folds in arachnids