practical 6

Question 1

chordates/ vertebrates traits

Answer 1

• Notochord
• Dorsal hollow nerve chord
• Pharyngeal bars and slits
• Endostyle
• Post-anal tail

Question 2

Vertebrates diversification

Answer 2

modification of ancestral chordate characters

Question 3

Vertebrate (Vertebrata) apomorphies

Answer 3

1. Cranium
2. Tripartate brain
3. Sense organs
4. Lateral line system
5. 2 chambered heart
6. Liver
7. Kidney
8. Hemoglobin
9. Vertebrae

Question 4

Cranium functions

Answer 4

• Brain protection
• Housing sensory organs (eyes,
  ears, olfactory organs)

Question 5

Tripartate Brain

Answer 5

• Larger brain = increased ability to process responses to environment
• Tripartate = 3 subdivisions
• Possibly related to evolution of more complex sensory organs

Question 6

Sense Organs

Answer 6

• coevolution with tripartite brain
• lateral line system: Receptors in the skin to sense vibrations/changes in water pressure
• Photosensory pineal organ (some
  vertebrates) = top of head, detects light, endocrine/hormonal functions

Question 7

Two-Chambered Heart

Answer 7

• Two chambered = one atrium + one ventricle
• evolved: Increased capillaries = increased respiratory efficiency, muscle required to pump blood more effectively to many tiny capillaries

Question 8

Liver function

Answer 8

• Proteins + fats = carbohydrates
• Old blood cells discarded
• Nitrogenous waste converted to urea or uric acid
• Glycogen (carb) storage

Question 9

kidney function

Answer 9

• waste removal
• maintaining solute equilibrium in the body

Question 10

Hemoglobin

Answer 10

• Respiratory pigment = proteins + metallic ions, responsible for red color of blood
• Function = increases blood oxygen content by binding with oxygen in the blood

Question 11

Vertebrae

Answer 11

• Hagfish and lampreys have rudimentary vertebrae = cartilaginous blocks
• Most vertebrates have bony vertebrae

Question 12

Myxini: hagfishes

Answer 12

jawless, mostly marine, scaleless, oral tentacles for feeding

Question 13

Petromyzontida: lampreys

Answer 13

• Anadromous = Migration
  from ocean to freshwater to
  reproduce, then juveniles
  swim to ocean
• jawless
• most parasitic

Question 14

Gnathostomata (jawed vertebrates)

Answer 14

• Jaws: evolved from first pair of pharyngeal bars, allowed for larger gape for feeding and/or defense
• Calcified teeth: improved feeding efficiency
• Heterocercal tail (ancestral): upper lobe stiffer than lower lobe, lift and acceleration: burst swimming

Question 15

Chondrichthyes: cartilaginous fish types of fish

Answer 15

• Sharks, rays, skates, ratfishes

Question 16

Chondrichthyes apomorphies and traits

Answer 16

• Features = all carnivorous, most marine, cartilaginous skeleton
• Apomorphies = claspers (male reproductive organ), placoid scales (“dermal denticles”)
  1. Elasmobranchii (sharks, skates, rays)
  2. Holocephali (ratfishes)

Question 17

Chondrichthyes: Elasmobranchii apomorphies

Answer 17

• Two fin spines (dorsal fins)
• Ampullae of Lorenzini = located around snout and head, detect electric fields to hunt prey
• spiracles = pump water over gills to breath

Question 18

Osteichthyes: Bony fish apomorphies

Answer 18

• Gas bladder = for buoyancy control or lung depending on taxon
• Adenticulate scales
• Bony opercula (sing. operculum) = covers gills, coordinate mouth and opercula to draw water over gills

Question 19

Actinopterygii: Ray- finned fishes

Answer 19

• Homocercal tail: vertebrae do not
  extend into upper lobe of caudal fin, symmetrical caudal fin
• Rays in pectoral and pelvic fins: good for maneuvering and stopping

Question 20

Sarcopterygii: Lobe-finned fish

Answer 20

• lobed, muscular pectoral fins
  Actinista: coelacanths = 3 lobed tail, only 2 extant species
  Dipnoi: lungfish = Breathe air for buoyancy control

Question 21

2 reasons sarcopterygians (tetrapod ancestors) may have left water

Answer 21

1. Droughts likely applied environmental pressure
2. Food availability: insects on land

Question 22

Tetrapoda synapomorphies

Answer 22

• Eyelids =prevent eyes from drying on land
• Stapes = inner ear bone: attaches to eardrum
• Atlas = allows for movement of side to side and up-down head movements
• 4 legs with 5 digits on each limb = motility on land

Question 23

Amphibia: Apoda (limbless lizards)

Answer 23

• appear segmented, eyes, nostrils
• Tentacle sense organ near the
  mouth

Question 24

Amphibia: Urodela (salamander, axolots)

Answer 24

• Sister to Anura = both groups lost bony body scales
• Distribution = Europe, Americas, Asia
• Aquatic larvae = external gills, some species retain aquatic larval
  characteristics into adulthood =
  paedomorphism

Question 25

Amphibia: Anura (frogs)

Answer 25

- Distribution: every continent besides Antarctica - Adaptations for jumping = hind limbs longer than forelimbs, lost ribs, elongated ilium - reproduction: Metamorphosis: egg to tadpole to larvae

Question 26

Anuran Habitat Adaptations

Answer 26

1. Pond dwellers = long webbed toes, powerful legs, streamlined body 2. Burrower = stout body, short limbs, feet may have spades, thick foot webbing 3. Arboreal = adhesive toe pads, elongated limbs and toes, small body size

Question 27

Amniota apomorphies

Answer 27

- Amniotic egg - Axis: allows for rotational head movement - Internal fertilization - Hard keratin (alpha keratin) = claws

Question 28

Reptilia Apomorphies

Answer 28

- Uric acid: nitrogenous waste excretion, efficient water absorption: can inhabit dry habitats - Scales with beta keratin - Bipedalism = facultative: has the ability to walk on two legs - Obligate: required to walk on two legs

Question 29

Reptilia: Testudines

Answer 29

- Bone covered in keratin scutes - Carapace: top of shell - Plastron: “belly” of shell - tortoise are only land animals while turtle are marine and land animals

Question 30

Reptilia: Squamata apomorphies

Answer 30

- Paired hemipenes * Enlarged Jacobson’s organ, paired with forked tongue = great sense of smell

Question 31

Squamata snake traits

Answer 31

- Limbless - No mobile eyelids - No external ear

Question 32

(4) squamata lizard traits

Answer 32

- Have legs - Usually have an eyelid - Usually have external ears - Tail autonomy = fracture plane

Question 33

Lizard Habitats Adaptations

Answer 33

- Sand dwelling = toe fringe, wedge-shaped head, flattened body - Arboreal = may have rounded toe pads (geckos etc.), dorsoventrally or laterally compressed body (gecko vs chameleon), some have prehensile tails or adhesive pads on tail tip - Burrowing = reduced/lacking limbs, generally elongate - Semiaquatic = laterally compressed tail - generalists = various environments and feed on whatever is available

Question 34

Reptilia: Archosauria Apomorphies

Answer 34

- 4 chambered heart - Nest building - Parental care

Question 35

Archosauria: Crocodylia adaptations for aquatic life

Answer 35

- Flat skull - conical homodont teeth in elongate jaw, homodont = all teeth same shape - Nostrils on top of head - Laterally compressed tail - Webbed feet

Question 36

Archosauria: Aves apomorphies and traits

Answer 36

- Powered flight - Pygostyle (shorted tail) - Keratin beak (no teeth) Other characteristics (shared with dinosaurs) - Hollow bones - Feathers (modified scales), barb, hooks, quills, rachis, barbule - Fercula: fused collarbones - Keeled sternum: muscle attachment

Question 37

Beak adaptations

Answer 37

- Sand prober * Insect eater * Insect netter * Water strainer * Raptor * Fish eater * Seed cracker