Chapter 34

have chordate larval forms, which metamorphose into sessile, filter-feeding adults that bear little resemblance to other chordates.

Tunicates, Urochordates, or Urochordata

What characteristics are found in vertebrates, but not tunicates or lancelets? Vertebrae A distinct head A notochord Pharyngeal slits

Vertebrae A distinct head

in echinoderms, the larvae are __ symmetrically, and the adults are __ symmetrical

bilaterally; pentaradially

What organisms are in the class Ophiuroidea?

brittle stars

Members of this phylum are characterized by a dorsal, hollow nerve cord, a notochord, pharyngeal gill slits, and a postanal tail.

chordata

Cephalochordates, or __ are small marine chordates

lancelets

What organisms are in the class Asteroidea?

sea stars

Despite how different their sessile, filter-feeding adult forms seem, larval ___ clearly display chordate features.

tunicates or urochordates

The nonvertebrate chordate subphyla are

urochordata and cephalochordata

The chordate subphyla are Urochordata, Cephalochordata, and

vertebrata

In echinoderms, the hydraulic system that aids in movement and feeding is called the Blank______.

water-vascular system

Amniotes appeared approximately _____ million years ago. Multiple choice question.

300

Vertebrate evolution is believed to have begun

545 mya.

Characteristic of echinoderms

Adults have pentaradial symmetry Deuterostome development Endoskeleton made of calcium carbonate plates

Organisms with spiny skin that exhibit pentaradial symmetry as adults, and have an endoskeleton made of calcium carbonate plates, are known as the ______.

Echinoderms Echinodermata

Enclosed dorsal nerve cord Brain encased in skull Three pairs of well developed sensory organs

Enclosed dorsal nerve cord Brain encased in skull Three pairs of well developed sensory organs

What best describes symmetry in echinoderms?

Free-swimming larvae have bilateral symmetry, while the adult form is pentaradially symmetrical

What are the four features that characterize all chordates?

Presence of a notochord during embryonic development Presence of a postanal tail Presence of pharyngeal slits or pouches in the embryo Presence of a single, hollow nerve cord