Biology 11 - Invertebrate Review Chart
PORIFERA (sponges)
 aquatic organisms that lack the true tissues and organs
 asymmetrical and sessile
 filter feeding
 budding (asexual) and sexual reproduction
CNIDARIA (jellyfish, anemone)
 radial symmetry
 Endoderm, ectoderm ( 2 germ layers - true tissues) and a mesoglea (jelly layer)
 digestive cavity with one opening
 most have tentacles armed with stinging cells (cnidocytes & nematocysts)
 Medusa and Polyp life stages
PLATYHELMINTHES (flatworms) *first to show bilateral symmetry
 un-segmented, bilaterally symmetrical
 3 germ layers (endoderm, ectoderm, and mesoderm)
 no body cavity (aceolomate)
 digestive cavity, if present, has only one opening, parasitic (tapeworm and flukes: requires 2
hosts) and free living species
 proglottids - sex organs that fall off the tapeworm
 scolex - head of the tape worm
 circulation: diffusion
 regeneration
 primitive brain - two nerve cords
NEMATODA (roundworms)
 pseudocoelomate, unsegmented, bilaterally symmetrical, one way tubular digestive tract
(evolutionary advantage over the flatworms)
 live in great numbers in soil and aquatic habitats
 many are parasitic (trichinella and ascaris: requires only 1 host)
 circulation: diffusion
 primitive brain - two nerve cords
MOLLUSCA (snails, clams, squid)
CLASSES:
GASTROPODA (stomach foot)(snail)
CEPHALOPODA(head foot) (squid)







soft body coelomates
bodies are divided into three parts
- head - foot
-visceral mass
-mantle
digestive tract has 2 openings
many have shells (produced by mantle)
have a radula (rasping tongue)
aquatic and terrestrial species
have gills
BIVALVIA (2 part shell)(clam)
ANNELIDA (segmented worms)
 coelomate
 segmented
*segmentation: allows for more specialization of tissues and organs and allows for more efficient
movement.






bilaterally symmetrical
complete digestive tract
terrestrial and aquatic
crop and gizzards
nephridia: excretory pores
brain with large nerve cord with many ganglia
ARTHROPODA (lobsters, insects, spiders, trilobites, millipedes)
 chitinous* exoskeleton covering segmented bodies
 paired, jointed appendages (legs)
 open circulatory system
 many have wings
 land and aquatic environments
 excretory organs - malpighian tubules
 insects have a tracheal system to connect cells to the environment for respiration
*chitin is a protein that makes the exoskeleton
sub-phyla
chelicerata: no antennae (includes class: arachnids)
crustacea: 2 pairs of antennae and modified branching appendages (lobsters, crabs, shrimp)
trilobitmorpha: extinct
uniramia: unbranched appendages, one pair of antennae (includes myriapods (millipedes) and
insects)
ECHINODERMATA (sea stars, sea urchins, sand dollars, sea cucumbers)
 radial symmetry (penta-radial body array around a central core)
 water vascular system - madreporite (also called a sieve plate) - stone canal - ring canal radial canal - ampulla - tube feet
 tube feet extend with ampulla muscular squeeze
 has a thin layer of epidermis so the skeleton is an endoskeleton (on the inside)
 echinoderm literally means spiny-skin
 regeneration and sexual reproduction
 all aquatic
 Deuterostome - Anus first, radial cleavage, closest relative to the vertebrates (phylum
chordata)
 respiration - oxygen diffusion
 closed circulatory system