Most plants are multicellular although a few algae are included within this group, some of which are single-celled or colonial. The gre en algae are important in both fresh water and marine systems. The red algae and brown algae are large algae that are almost exclusively marine. Other plants th at are found in aquatic situations are small plants like mosses and flowering pl ants such as water lilies and cattails.

E. Animal. This kingdom consists of multi-cellular organisms that cannot make their own food and depend directly or indirectly on plants. Most animals ha ve fairly complex structure with specialized systems for movement, digestion, et c. Most also have nervous systems to help coordinate the organisms activities. A nimals tend to be divided into two basic types--vertebrates (animals with backbo nes) and invertebrates. The vertebrates include fish, amphibians, reptiles, bird s and mammals. You should see representatives of all these groups on your field trips.

There are many phyla of invertebrates. Some of the more common anim als that you are likely to see include the following:

1. Sponges (Phylum porifera).

These are simple organism which consist of an outer layer of cells and an inner layer which surrounds a network of internal pores and canals. These organisms are sessile (are attached to the substrate an d do not move). Most are marine although there are freshwater sponges in our loc al area. These sponges don't look like typical animals--most appear as a mass of cells attached to sticks or other structures in the water.

2. Hydra, Jellyfish and Sea Anemones (Phylum cnidaria).

These are simple organisms that float in the water (jellyfish types) or move sl owing along a subs trate (hydras and sea anemones). Most capture small organisms with their tentacl es which surround their mouths. You will see hydras in the lab and possibly in t he field. Corals are also members of this group.