BIO 104 4/30/96

REVIEW OF LAST NIGHTS EXAM  - RANGE 24 - 100; MEAN 71%

Continue material in Chapter 29-Animal Diversity
               # of species        Margulis
Porifera         5,000               10,000
Cnidaria         9,000                9,500
Platyhelmeths   13,000               15,000
Nematoda        12,000               80,000
               -400-500,000 including fossils          
Mollusca        47,000              110,000 (2nd largest phylum)
               -35,000 fossil
Annelida         9,000                9,000
Arthropoda     1,000,000            500,000 described 
                                 10,000,000 insects (estimated)
     -Arthropoda is the largest phylum by far
Echinodermata    6,000                6,000
               -20,000 fossil
Chordata        45,000               45,000

Very few chordates in relation to the total number of animals.

Phylogenetic Tree:



Phylum Mollusca
     about 110,000 living species
     about 35,000 of these are fossil species
1) have a mantle
     -tissue that secretes/forms a shell
     A. shells
          1. one piece shells: snails
          2. two piece shells: clams
          3. eight piece shells: chitons
     B. Mantle forms a mantle cavity which may house:
          1) gills
          2) lungs
          3) reproductive systems
2) Muscular "foot" for locomotion
     A. foot
          1. flat sole (snails)
          2. compressed (clams)
          3. arms or tentacles (squid)
SEE PAGE 553

3 Types of Mollusks:
     1. Gastropod
     2. Bivalve
     3. Gephalapode
All mollusks except bivalve have radula which is used to scrape food
Mollusks have both an open and a closed circulatory system (cephalopoda)
3 Classes of Mollusks:
     1. Gastropoda
          -coiled shell; including snails and slugs
     2. Peleypoda (bivalves)
          -hinged shells:  clams and oysters
     3. Cephalopoda
          -head with tentacles:  squid, octopus

Phylum Arthropoda
     -segmented body
     -external skeleton: exoskeleton
     -nerve cord is ventral rather than dorsal
     -open circulatory system

3 main classes
     1. Crustacea
          -2 pairs of antennae
          -respire by gills
          -lobster, crayfish, crab, shrimp, barnacle, pill 
               bugs