Exam 31: Animal Phylogeny, Acoelomates, and Protostomes

Most members of the ____ Cnidarian lineage, including Obelia species, have both polyp and medusa stages in their life cycles, with the polyp stage typically forming a colony.

Most biologists agree that the most recent common ancestor of all animals was probably a ____, an idea first proposed by Ernst Haeckel in 1874.

How do the nervous systems of cnidarians and arthropods differ?

Ringlike patterns on an earthworm and "six-pack abs" in humans are evidence of ____ in an animal's body plan.

Most mollusks have a closed circulatory system in which hemolymph is confined within the walls of hearts and vessels. ​

Which life history patterns in some rotifers are adapted to living in small bodies of water?

Members of the phyla Ectoprocta, Brachiopoda, and Phoronida all possess a lophophore, which isa(n)____.

Members of the ____ phylum have radial symmetry, nematocysts,and polyp and/or medusa body forms as adults.

In most eumetazoans, the nervous system is derived mainly from which embryonic cell layer?

Members of the ____ subphylum, including spiders, ticks, mites, scorpions, and horseshoe crabs,have fanglike appendages used for biting prey and pedipalps used as grasping organs, sensory organs, or walking legs.

In deuterostomes, early embryos undergo ____ cleavage.

Animals are ____ organisms, and their cells ____ cell walls.

The ____Lophotrochozoan phylum contains the most species, with about 100,000 living species described.

Members of the ____ subphylum are now all extinct, but they were extremely numerous in shallow Paleozoic seas. Most of them were dorsoventrally flattened and heavily armored, with two deep longitudinal grooves that gave their body a three-lobed appearance.

Most Hydrozoan polyps form sessile colonies that develop asexually from one individual.

Only 180 living species of velvet worms, characterized by jaws, an open circulatory system, and relatively large brains, comprise the ____ Ecdysozoan phylum.

Ctenophores capture their food with feeding tentacles.