Nudibranches (Order Nudibranchia) are found worldwide. These marine shell-less, snail-like animals crawl along the bottom of the ocean. Many species are approximately one foot in length. Nudibranches are beautifully colored. When disturbed, some species fill the water with a large amount of dark dye for protection.

Gastropods (Class Gastropoda) contain the snails, conchs, and similar snail-like animals. There are about 105,000 species of gastropods. This class is divided into several separate orders:

    Sub Class Streptoneura (57,000 species)

      Order Diotocardia:   Two sets of organs
      Order Monotocardia:  One set of organs
    
    Sub Class Euthyneura   (48,000 species)

      Order Cephalaspidea: thin shells, etcetera
      Order Nudibranchia:  sea slugs        
      Order Pulmonata:     snails and slugs

Mollusks (Phylum Mollusca) are a large and varied group of animals. Some species are found on land; others are found in freshwater; many are found in the oceans of the world. The most familiar mollusks have an external shell surrounding a soft body. Well-known examples of mollusks are snails and clams. The major classes are as follows:
  
   Ablacophora:                  Worm appearing
   Polhyplacophora (Amphineura): Chitons
   Scaphopoda:                   Tusk Shells
   Gastropoda:                   Gastropods
   Bivalvia (Pelecypoda):        Clams, etcetera
   Cephalopoda:                  Octopus, Nautilus
   Monoplacophora:               A recent discovery

Animal Kingdom contains numerous organisms that feed on other animals or plants. Included in the animal kingdom are the lower marine invertebrates such as sponges and corals, the jointed legged animals such as insects and spiders, and the backboned animals such as fish, amphibians, reptiles, birds, and mammals.