Chaoter 34: Vertebrates (1)

Question 1

What are the 4 key characters of chordates?

Answer 1

Four key characters of chordates
– Notochord
– Dorsal, hollow nerve cord
– Pharyngeal slits or clefts
– Muscular, post-anal tail

Question 2

What are chordates?

Answer 2

Chordates - are bilaterian animals that belong to the clade of animals known as Deuterostomia

Question 3

What do chordates comprise of?

Answer 3

Chordates comprise:
– all vertebrates
– two groups of invertebrates
a) urochordates
b) cephalochordates

Question 4

What is the notochord and its function?

Answer 4

The notochord is a longitudinal, flexible rod between the digestive tube and nerve cord

• It provides skeletal support throughout most of the length of a chordate

Question 5

In most chordates, grooves in the pharynx called _____ develop into slits that open to the outside of the body

Answer 5

In most chordates, grooves in the pharynx called pharyngeal clefts develop into slits that open to the outside of the body

Question 6

What are the pharyngeal slits function?

Answer 6

Functions of pharyngeal slits
– suspension-feeding structures in many invertebrate chordates
– gas exchange in vertebrates (except vertebrates with limbs, the tetrapods)
– develop into parts of the ear, head, and neck in tetrapods

Question 7

What are lancelots?

Answer 7

• lancelets are marine suspension feeders
  that retain characteristics of the chordate
  body plan as adults
• Adult lancelets are about 6cm long
• Adults swim down the sea floor and
  wiggles into the sand leaving the anterior
  end exposed

Question 8

What are tunicates?

Answer 8

• Tunicates mostly resemble chordates during their larval stage, which may last only a few minutes
• As an adult, a tunicate draws in water through an incurrent siphon, filtering food particles
• Larvae use tail muscle and notochord to swim through water in search of suitable substrate
• On suitable substrates, tunicates undergo radical metamorphosis: chordate characters disappear e.g.
• Tail and notochord are resorbed
• Nervous system degenerates