Chap. 34 (1)

Question 1

Chordates (phylum Chordata) are _____ animals that belong
to the clade of animals known as _____.

Answer 1

bilaterian
Deuterostomia

Question 2

Chordates comprise all vertebrates and two groups of invertebrates, the (2).

Answer 2

urochordates and cephalochordates

Question 3

Four key characters of chordates

Answer 3

• Notochord
• Dorsal, hollow nerve cord
• Pharyngeal slits or clefts
• Muscular, post-anal tail

Question 4

notochord

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

Dorsal, hollow nerve cord

Answer 5

The nerve cord develops into the central nervous system: the brain and the spinal cord

Question 6

Pharyngeal slits or clefts

Answer 6

In all chordate embryos, grooves form along the outer surface of the pharynx called pharyngeal clefts
* In most chordates, these grooves develop into pharyngeal slits that open to the outside of the body

Question 7

Pharyngeal slits functions (3)

Answer 7

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 8

Muscular, post-anal tail

Answer 8

Chordates have a tail posterior to the anus
* In many species, the tail is greatly reduced during embryonic development
* The tail contains skeletal elements and muscles
* It provides propelling force in many aquatic species

Question 9

Lancelets (Cephalochordata)

Answer 9

• are named for their bladelike shape
• They are marine suspension feeders that retain characteristics of the chordate body plan as adults

Question 10

Tunicates (Urochordata)

Answer 10

• are more closely related to other chordates than
  are lancelets
• Tunicates most resemble chordates during their larval stage, which may
  last only a few minutes

Question 11

A skeletal system and complex nervous system have allowed
vertebrates to be efficient at two essential tasks…..

Answer 11

• Capturing food
• Evading predators

Question 12

The neural crest

Answer 12

cells that appear along the edges of the closing neural tube of an embryo, is another unique feature of vertebrates

Question 13

lineages of jawless vertebrates remain today (2)

Answer 13

the hagfishes and the lampreys
-lack backbone but have rudimentary vertebrae

Question 14

cyclostomes

Answer 14

clade of jawless vertebrates

Question 15

gnathostomes

Answer 15

Vertebrates with jaws make up a much larger clade

Question 16

Other characters common to gnathostomes (3)

Answer 16

• Genome duplication, including duplication of Hox genes
• An enlarged forebrain associated with enhanced senses of smell and vision
• The lateral line system

Question 17

The lateral line system

Answer 17

rows of organs sensitive to vibrations that are located along each side of the body of aquatic gnathostomes

Question 18

Chondrichthyans (4)

Answer 18

• have a skeleton composed primarily of cartilage
• The largest and most diverse group of chondrichthyans includes the sharks, rays, and skates
• A second group is composed of a few dozen species of ratfishes, or chimaeras
• have a short digestive tract with a spiral valve that increases surface area and slows the passage of food

Question 19

Chondrichthyans embryos developments (3)

Answer 19

• Oviparous: Eggs hatch outside the mother’s body
• Ovoviviparous: Eggs are retained within the oviduct; young are born after hatching within the uterus
• Viviparous: The embryo develops within the uterus and is nourished from the mother’s blood through a yolk sac placenta

Question 20

The vast majority of vertebrates are _____.

Answer 20

osteichthyans
- include the bony fishes and tetrapods

Question 21

Tetrapods have some specific adaptations (5)

Answer 21

• Four limbs and feet with digits
• A neck, which allows separate movement of the head
• Fusion of the pelvic girdle to the backbone
• The absence of gills (except some aquatic species)
• Ears for detecting airborne sounds

Question 22

Tiktaalik, nicknamed a “fishapod,”

Answer 22

shows both fish and tetrapod
characteristics
* Traits it shares with fish include fins, gills, lungs, and scales

Question 23

Amphibians three clades

Answer 23

• Salamanders (Urodela, “tailed ones”)
• Frogs (Anura, “tail-less ones”)
• Caecilians (Apoda, “legless ones”)

Question 24

Salamanders (Urodela) are…. (3)

Answer 24

• amphibians with tails
• Some are aquatic, but others live on land as adults or throughout life
• Paedomorphosis, the retention of juvenile features in sexually mature
  organisms, is common in aquatic salamanders

Question 25

Frogs (Anura)

Answer 25

• lack tails and have powerful hind legs for locomotion on land
• Frogs with leathery skin are called “toads”

Question 26

Caecilians (Apoda) are….. (2)

Answer 26

• legless, are nearly blind, and resemble earthworms
• The absence of legs is a secondary adaptation

Question 27

amphibian Fertilization

Answer 27

• Fertilization is external in most species, and the eggs require a moist environment
• In some species, males or females care for the eggs on their back, in their mouth, or in their stomach

Question 28

amphibian pop. decline causes (4)

Answer 28

The causes include a disease-causing chytrid fungus, habitat loss, climate change, and pollution