Concept 34.2: Vertebrates are chordates that have a backbone

Flashcards from Concept 34.2 of Pearson's Campbell Biology, Twelfth Edition.

Vertebrates

Chordates that have a backbone, skeletal system, and complex nervous system that enables efficiency in capturing food and evading predators

• These have two or more sets of Hox genes while other chordates only have one

  • Enables nervous system evolution and skeleton innovations

Neural crest

Vertebrate characteristics appearing along the edges of the closing neural tube, dispersing through the embryo and giving rise to:

• Teeth

• Some bones and cartilage of the skull

• Several types of neurons

• Sensory capsules

Cyclostomes

A clade including hagfishes and vertebrates with the only living vertebrates lacking jaws and a backbone; however, these do have rudimentary vertebrae

Hagfishes

Jawless vertebrates with reduced vertebrae and a cartilaginous skull

• These retain the notochord and have eyes, ears, a small brain, and nasal opening connected to the pharynx

• Mouth contains tooth-like keratin formations

• All species of these are marine and most are bottom-dwelling scavengers

• Rows of slime glands produce a slime to repel competitors and predators

Lampreys

Jawless vertebrates with reduced vertebrae, a notochord, and cartilaginous skeleton

• Includes about 38 species in marine and freshwater environments

• Larvae live and feed in streams for several years

• Parasitic species migrate to oceans or lakes, clamping with mouths onto host fish to feed

Haikouella

The most primitive fossil found documenting the transition to vertebrates

• Were 3-cm-long suspension feeders resembling lancelets

• Had a well-formed brain, eyes, and muscular segments, but lacked a skull and ear organs

Head

A part of vertebrates consisting of a brain, eyes, other sensory organs, and a skull, enabling more complex movement and feeding behaviors

• First seen in Myllokunmingia with eye and ear capsules but lacking vertebrae

Conodonts

The earliest vertebrates in the fossil record, dating to 500 mya, capturing prey with large eyes and mineralized barbed hooks in the pharynx