Animal Evolution: Invertebrates

Animals are thought to be most closely related to ___________________

• choanoflagellates.

• charophytes.

• chytrids.

• fungi.

Major trends in the evolution of animals include _________________

• cephalization, the development of a definite head region.

• the development of types of symmetry.

• variation in coelomic cavities.

• all of the above.

Which structure insulates various internal organs from the stresses of body-wall movement and bathes them in a liquid through which nutrients and waste products can diffuse?

• a coelom

• mesoderm

• a mantle

• a water-vascular system

The repetition of body parts along the length of an animal’s body is termed ___________

• cephalization.

• coelomization.

• segmentation.

• compartmentalization.

Which of the following statements most accurately describes the deuterostomes?

• The first opening on the embryo becomes the mouth.

• Food and wastes enter/exit through the same body opening.

• They have an incomplete digestive system.

• The mouth developes from the second embryonic opening, and the first opening becomes the anus.

Which statement about sponges is correct?

• Sponges have two germ layers, which give rise to well-organized tissues.

• Most sponges have bilateral symmetry.

• Sponges belong to the group of invertebrates known as cnidarians.

• Sponges are filter feeders.

Feeding in sponges is dependent on ______________.

• choanocytes

• pores

• water flow

• all of the above.

Nematocysts are ________________

• reproductive cells.

• excretory organs.

• circulatory cells.

• defensive cells.

A flatworm lacks ___________

• bilateral symmetry.

• a true coelom.

• mesodermal tissue.

• bilateral symmetry and a true coelom.

A scolex is ______________

• the anterior attachment organ of a tapeworm.

• the feeding organ of a fluke.

• an appendage of a sandworm.

• the egg of a sea star.