Aquatic Invertebrates

I. What is an Invertebrate? A. Animals without backbones B. Each group possess special adaptations to survive in an aquatic environment. C. A major contributor for the aquatic food web. D. Break down organic matter E. Many are a good indicators of the health of aquatic environments

2. So What’s in the Water A. Microscopic Organisms 1. Zooplankton a. tiny free-swimming animal-like organisms b. mostly tiny crustaceans and rotifers c.important food source for small fish

2. Phytoplankton-plant-like organisms a. Photosynthetic organisms b. Size-microscopic, unicellular, colonial, to several large multicellular organisms c. Contains chlorophyll-requires sunlight to live and grow- lives in the euphotic zone. d. Often buoyant to remain near the surface. e. Requires nutrients such as nitrates, phosphates and sulphur f.Primary producer in the food chains g.Consumed primarily by zooplankton h.Accounts for half of all photosynthesis on earth

i.Types a.Cyanobacteria-algae 1.Various colors 2.Can convert atmospheric N 2 into an organic form b.Diatom-algae 1.encased in a silica 2.contains oil 3.used in toothpaste (grit) c.Dinoflagellates-algae 1.know as fire-algae 2.moves with a flagella 3.Causes “red tide”

d. Green algae 1.Unicellular, colonial or multicellular 2.Size-microscopic to large multicellular

B. Aquatic Insects 1.Found in fresh and brackish water, NOT in saltwater 2. Two phases of development a.Metamorphosis-larvae, developments into adult b.Nymph or larvae lives in water c.Adult-live in water, land or air. d.Example: saltwater mosquitoes C.Crustaceans 1.Found in freshwater and saltwater 2.Have an exoskeleton-for protection and support 3.Examples: crayfish, shrimp, crab, lobsters

D. Other organisms in the water 1.Mollusks-soft-bodied animals a.Found in freshwater and saltwater b.Wide variety of forms c.Some species have a shell d.Examples: clam squid, oysters, scallops, octopus