Dichotomous Key

Animals are placed in taxonomic classifications based on differences and similarities of their traits. If you know what critical traits to look for, it is possible to separate any animal into a taxonomic category.

The common categories are Domain, Kingdom, Phylum, Class, Order, Family, Genus and Species (Specific Epithet.)

Example: Human Classification

Domain: Eukarya

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Hominidae

Genus: Homo

Species: sapiens

Scientific name: Homo sapiens

Part 1: The assignment document contains a table with images. The images are examples of nine Animal Phylum: Porifera, Cnidaria, Nematoda, Athropoda, Platyhelminthes, Annelida, Mollusca, Echinodermata, and Chordata.

Use the Dichotomous Key to determine the taxonomic category (phylum or class as shown on the key) for each animal (picture), and write these categories under the Classification Column on the table.

You will also need to list the phylum for each animal picture in column one; and list in column 2 all the steps chosen when using the key to arrive at the classification for each animal.

For help on how to use the Dichotomous Key, download and review the document called How to use the Dichotomous Key.

Part 2: Answer the following questions as it relates to the nine phyla in the assignment table. (Porifera, Cnidaria, Nematoda, Athropoda, Platyhelminthes, Annelida, Mollusca, Echinodermata, and Chordata.)

Which phyla lack organs? What type of symmetry do they have?
List all of the phyla that show cephalization?
Do all organisms on the table have 3 germ layers (endoderm, ectoderm and mesoderm)? If not, which Phyla have fewer than three germ layers?
One phylum has more species than all the others. State the name of this phylum and provide several different examples of species found in this phylum.
Facts state, fish do not all have the same skeletal structure. Describe the differences among fish from the most primitive to more advanced types.
Describe the three types of mammals based on how their young develop.