Aquatic Invertebrates

I. What is an Invertebrate?

A. Animals without backbonesB. Each group possess special

adaptations to survive in an aquatic environment.

C. A major contributor for the aquatic food web.

D. Break down organic matterE. 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 rotifersc. 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 chainsg. Consumed primarily by zooplanktonh. Accounts for half of all photosynthesis

on earth

i. Typesj. Cyanobacteria-algae

1. Various colors2. Can convert atmospheric N 2

into an organic form b. Diatom-algae

1. encased in a silica2. contains oil3. used in toothpaste (grit)

c. Dinoflagellates-algae1. know as fire-algae2. moves with a flagella3. Causes “red tide”

d. Green algae1. Unicellular, colonial or

multicellular2. Size-microscopic to

large multicellular

B. Aquatic Insects1. Found in fresh and brackish water, NOT in

saltwater2. Two phases of development

a. Metamorphosis-larvae, developments into adult

b. Nymph or larvae lives in waterc. Adult-live in water, land or air.d. Example: saltwater mosquitoes

C.Crustaceans1. Found in freshwater and saltwater2. Have an exoskeleton-for protection and

support3. Examples: crayfish, shrimp, crab, lobsters

D. Other organisms in the water 1. Mollusks-soft-bodied animals

a. Found in freshwater and saltwaterb. Wide variety of formsc. Some species have a shelld. Examples: clam squid, oysters, scallops,

octopus