Animal Groups (pg24)

Question 1

Animals or Animalia

Answer 1

Organisms that obtain nutrition from other organisms and whose bodies are built of many cells, all of which lack cell walls

Question 2

Eumetazoans

Answer 2

Animals with integrated multicellular body structure, with cells organized in tissues.

Includes all animals other than sponges, which lack tissues.

Question 3

Bilaterians

Answer 3

All descendants of eumetazoans with a single line of symmetry, featuring a front end, usually with a head.

Bilaterians include nearly all animals, even those that have a radial (wheel-like) arrangement.

Question 4

Ecdysozoans

Answer 4

Bilaterally symmetrical animals with a 3-layered outer covering that is molted.

Most Ecdysozoans are arthropods, but roundworms are also abundant.

Question 5

Panarthropods

Answer 5

Ecdysozoans with limbs or claws.

This group is dominated by arthropods, but also includes the obscure velvet worms and tardigrades.

Question 6

Arthropods

Answer 6

Panarthropods with a rigid outer layer and jointed limbs.

Arthropods form by far the most diverse animal group, and examples include insects, spiders, scorpions, crabs, shrimps, barnacles, and millipedes.

Question 7

Lophotrochozoans

Answer 7

Bilaterians whose larva is of a unique type called a trochophore.

This group is dominated by mollusks but has other important members.

Question 8

Mollusks

Answer 8

Lophotrochozoans whose ancestors evolved a radula (rasping “tongue”), a muscular foot, and a body cover called a mantle. Not all mollusks retain these.

Question 9

Deuterostomes

Answer 9

Bilaterians with a radial pattern of cell division in the early embryo.

They include some invertebrates plus chordates, the group containing vertebrates.

Question 10

Enchinoderms

Answer 10

Dueterostomes with a spiny, chalky skeleton and a water vascular system, but no central nervous system.

Most have a radial body plan without a head.

Question 11

Chordates

Answer 11

Deuterostomes with a nerve chord along the back and a rod (notochord) supporting the body.

Sea squirts only have notochords as larvae.

Question 12

Craniates

Answer 12

All chordates that possess a skull.

Most craniates are vertebrates. Hagfishes are the only invertebrate craniates - they have a skull, but no vertebrae

Question 13

Vertebrates

Answer 13

Craniates that have a skull and a nerve chord along the back, and a notochord that develops into a vertebral column - the spine, or backbone. Vertebrates are generally the largest animals in most habitats and include fishes, amphibians, reptiles, birds, and mammals.