Chapter 33 terms and concepts

Question 1

Discuss how sponges are different from all other major groups of animals

Answer 1

They are basal animals, that lack tissues. They are sedentary and live in both marine or fresh water environments, and are also filter feeders

Question 2

Characterize cnidarians and describe their body plans

Answer 2

A wide range of both sessile and motile forms of organisms, including jellies, corals and hydras.

Diplopastic, radially symmetrical organisms. They also have a basic body plan of a sac with a central digestive compartment: gastrovascular cavity

Question 3

Cnidarian body plans

Answer 3

A polyp: adheres to a substrate by opposite end of its body from the mouth/anal opening

A medusa has a bell-shaped body with its mouth on underside

Question 4

Characteristics of lophotrochozoans

Answer 4

• Widest range of animal body form, related mostly by molecular data rather than morphological similarities

They have triploblastic development, and most have a coelom and a digestive tract with two openings

They have a lophophore - a crown of ciliated tentacles around their mouth that is used for feeding. Most have a true coelom

Question 5

Body plan of flatworms - do they have a true coelom?

Answer 5

Many are parasites.

They are acoelomates, meaning they lack a body cavity. They also have a gastrovascular cavity, with only one opening

Question 6

General characteristics of Ecdysozoans, including nematodes and arthropods

Answer 6

Most ecdysozoans are covered by a tough outer coating called the cuticle

Arthropods body plan: they have segmented, hard exoskeleton and jointed appendages, which can be modified for functions such as walking, feeding, sensory reception, reproduction, and defense. They have eyes, olfactory receptors, and antennae that function in touch and smell. They also have an open circulatory system in which hemolymph is circulated into spaces surrounding tissues and organs

Question 7

Spider and lobster (arthropods) body segments

Answer 7

They have a cephalothorax - which is a fused head and thoracic region designed for sensing, feeding and locomotion

Abdomen: houses digestive, reproductive and respiratory organs

Question 8

Compare/Contrast the major phylogenetic groups of animals

Answer 8

Sea stars and sea urchins are echinoderms (phylum Echinodermata)

Vertebrates (animals that have a backbone) are in phylum chordata. Which they constitute clade deuterostomia, which is mainly defined by DNA similarities