Chordates

Question 1

what are the 5 characteristics of chordates

Answer 1

1. notochord
2. dorsal hollow nerve chord
3. pharyngeal slits
4. endostyle for filter feeding
5. postanal tail for propulsion

Question 2

notochord

Answer 2

• becomes the vertebral column in Gnathostomata
• persists in jawless vertebrates and protochordates
• organizational role in development of nervous system

Question 3

dorsal hollow nerve chord

Answer 3

-dorsal to the digestive tract

Note: invertebrates have a nerve chord, but it is ventral and solid

Question 4

endostyle or thyroid

Answer 4

endostyle is present in protochordates and lamprey larvae. It secretes mucus that traps food particles brought to the pharyngeal cavity.
Thyroid gland regulates metabolism and hormones

Question 5

protochordata

Answer 5

do not have a true brain, skull, vertebral column

Question 6

craniata

Answer 6

have a skull, vertebral column

vertebrata

Question 7

Gnathostomata

Answer 7

craniates with jaws

Question 8

placoid scales

Answer 8

• Small, conical, toothlike structures
• Typical of chondrichthyes
• Modified to teeth in sharks

Question 9

Ganoid scales

Answer 9

• Diamond shaped

* Early bony fishes and living gars

Question 10

Cycloid and Ctenoid scales

Answer 10

• Arranged in overlapping rows

* Typical of teleost fish

Question 11

Chondrychthes

Answer 11

• No swim bladder (use tail to provide upward lift)
• Heterocercal tail: assymetrical, provides lift
• cartiligenous

Question 12

osmotic regulation of freshwater fish? marine fish?

Answer 12

freshwater: hyperosmotic regulators
marine: hypoosmotic regulators

Question 13

hyperosmotic regulators

Answer 13

• greater concentration of salt in the fish
• water only enters through membranes (gills)
• diluted urine
• kidneys push water out of the fish
• salt-absorbing cells in the gill move salt from the water to the fish

Question 14

hypoosmotic regulators

Answer 14

• contain a small amount of salt than the surrounding water
• salt-secretory cells in the gill move salt out of the body
• salt is voided in feces or excreted by the kidney

Question 15

How do gills work?

Answer 15

idk

Question 16

Myxini

Answer 16

• Jawless
• Entirely marine group
• Feed on annelids, molluscs, crustaceans, and dead or dying fishes
• Scavengers and predators (not parasitic)
• Poorly developed eyes
• Keenly developed sense of smell and touch
• Produce slime as a defense mechanism
• Can tie itself into a knot
• Has a rasping organ (keratinized scales on tongue)

Question 17

rasping organ?

Answer 17

snail, Myxini, Petromyzontida (so Agnatha)

Question 18

Petromyzontida

Answer 18

• They use tooth-like plates of keratin for rasping a hole, through which fluids and tissues are sucked.
• half are parasitic

Question 19

Actinopterygii

Answer 19

Symmetrical homocercal tail allows for greater speed

• swim bladder
• gills

Question 20

Sarcopterygii

Answer 20

Diphycercal tails

lungs and gills

Question 21

Urochordata

Answer 21

• tunicates
• Only the larval form bears all the chordate hallmarks
• solitary or colonial
• Most sessile as adults, some free-living

Question 22

Cephalochordata

Answer 22

• Lancelets
• Originally bore the generic name Amphioxus
• Amphioxus: Greek, amphi, both ends + oxys, sharp
• Modern survivors of an ancient chordate lineage
• Slender, laterally compressed, translucent animals
• Inhabit sandy sediments of coastal waters
• 5 distinct characteristics of chordates but in simple form
• Lack features found in true vertebrates • No brain

Question 23

what are the adaptations of amniotes

Answer 23

1. Amniotic egg
2. Thicker and more waterproof skin
3. Rib ventilation of the lungs
4. Stronger jaws
5. High-pressure cardiovascular systems
6. Water-conserving nitrogen excretion
7. Expanded brain and sensory organs