Draw a cladogram for the following animals: sponges, cnidarians, flatworms, echinoderms, chordates, mollusks, annelids, nematodes, and arthropods. On your cladogram indicate the points where the following evolved: (1) true tissues, (2) bilateral symmetry, (3) three germ layers, (4) segmentation, (5) protostome development, and (6) deuterostome development.

Cladogram

A diagram used in cladistics which shows relations among organisms based on the presence of shared characteristics not found in their ancestors.

Bilateral Symmetry

A type of body symmetry where the body can be divided into identical left and right halves along a single plane.

Protostome Development

A mode of animal development in which the mouth forms before the anus during embryogenesis, characteristic of mollusks, annelids, and arthropods.