Morphology and Physiology

Question 1

what body form did early vertebrates have?

Answer 1

were aquatic, limbless filter-feeding fish

Question 2

what shape is a fish and the adaptation of this

Answer 2

Fusiform shape (tapered ends) for minimal resistance (Oeffner & Lauder, 2012), especially effective due to denticle-enhanced propulsion in sharks

Question 3

how did morphology change when vertebrates moved to land

Answer 3

o Movable head, longer neck; tail reduced (balance not propulsion).
o Fins → limbs (e.g., jumping, flying).
o Limb loss in burrowers.

Question 4

how did morphology change for flight evolution

Answer 4

o Wings, keeled sternum (birds), fused bones.
o Elongated digits (bats).

Question 5

what does integument mean and how much body weight does it make up

Answer 5

skin and derivatives. the outer layer of the body. 15-20% but more in armoured species

Question 6

what is the function of integument

Answer 6

protection, sensation, respiration, thermoregulation

Question 7

what is the composition of integument

Answer 7

Epidermis (ectoderm), Dermis (mesoderm; vertebrate-specific).

Question 8

what integument do fish have?

Answer 8

Dermal scales; epidermal glands secreting mucus (drag reduction).

Question 9

what are the benefits of shark skin denticles?

Answer 9

skin denticles enhance swimming speed by 12.3% compared to rigid skin plates (reducing drag and increasing thrust) Oeffner, J. and Lauder, G.V. (2012).

Question 10

how does land vertebrates integument differ?

Answer 10

Stratum corneum (keratinised) evolved to reduce water loss. S. corneum thin in amphibians but thicker in terrestrial vertebrates

Question 11

how have diving birds (dippers) adapted their integument

Answer 11

feathers are usually for thermoregulation and display but Adapted feather structures resist water penetration (essential for underwater foraging) while retaining water repellency (Rijke & Jesser, 2010).

Question 12

function of the skeleton

Answer 12

support, protection and movement of muscles

Question 13

what does bone replace during development?

Answer 13

cartilage

Question 14

how does the skeleton of fish and tetrapods differ?

Answer 14

o Fish: Trunk, caudal.

o Tetrapods: Cervical, thoracic, lumbar, sacral, caudal.

Question 15

how do mammals differ in their skeleton to other vertebrates?

Answer 15

evolved a modular, regionalised spine

Question 16

what was the process of evolution of the spine in mammals?

Answer 16

Early synapsids has 3 spinal regions, Therapsids evolved a 4th (pectoral) and early mammals a 5th (lumbar).

Question 17

what is the benefit of having 5 regions of the spine?

Answer 17

Five distinct regions allow diverse locomotion (Pennisi, 2018).

Question 18

what is the evolutionary trade-off in the 5th region in humans?

Answer 18

lumbar is linked to common back problems in humans

Question 19

what are the differences in musculature in fish, land vertebrates and fliers

Answer 19

• Fish: Myomeres (chevron-shaped), segmental contractions.
• Land vertebrates: Muscles intrinsic to limbs for complex movement.
• Fliers: Enlarged appendicular, reduced axial muscles.

Question 20

what appendages do fish have?

Answer 20

Paired (pectoral/pelvic) and unpaired (dorsal/anal) fins

Question 21

how has appendages evolved in terrestrial vertebrates

Answer 21

Fins modified into limbs (girdle + digits).
o Locomotion diversity (e.g. jumping frogs, running ostriches).

Question 22

what is the adaptation of digit loss in cursorial mammals e.g. horses?

Answer 22

enabled high-speed locomotion and is a response to increased body mass.
explanations for this transition include:
- Faster locomotion in open grasslands (longer, slender legs for speed).
- Reduced energy costs of movement (less distal limb mass)

Question 23

what did McHorse et al. 2017 state to support digit reduction?

Answer 23

Reduction supported by increased metapodial strength and stress-bearing adaptation. Horses evolved from four-toed ancestors (Hyracotherium) to modern single-toed Equus, likely due to changes in habitat, locomotion, and body mass.

Question 24

why did fish evolve gills

Answer 24

needed due to low oxygen levels in the water

Question 25

what is the process of respiration in fish through their gill arches?

Answer 25

Water flows over secondary lamellae, while blood flows through capillaries inside them. A thin barrier allows oxygen to diffuse from water into blood due to a concentration gradient. The counter-current flow keeps this gradient constant, ensuring efficient oxygen transfer.

Question 26

how do land vertebrates and amphibians differ?

Answer 26

* Land vertebrates: Lungs (vascularised, high surface area). * Amphibians: Use skin and lungs variably with activity and temperature.

Question 27

why are air and water breathers different? (Johansen & Lenfant), (Scott, 2015).

Answer 27

found air breathers required lower ventilation rates than water breathers due to the higher oxygen availability in air. air breathers developed low haemoglobin affinity to unload oxygen efficiently

Question 28

what about bird and mammals respiration?

Answer 28

4-chambered heart and efficient lungs support high metabolic demands

Question 29

describe the difference in circulatory physiology in fish, amphibians/reptiles and birds/mammals

Answer 29

* Fish: 2-chambered heart, single circuit. * Amphibians/Reptiles: 3-chambered, partial blood mixing. * Birds/Mammals: 4-chambered, separate pulmonary/systemic circuits

Question 30

why are all vertebrate groups circulatory systems different

Answer 30

* Evolution supported greater activity levels and thermoregulation (Scott, 2015).

Question 31

why did heterotrophic nutrition evolve?

Answer 31

increased activity = higher energy needs

Question 32

how does the kidneys differ in evolution for Hagfish, fish/amphibians and terrestrial vertebrates

Answer 32

Hagfish: Pronephros. Fish/Amphibians: Opisthonephros. Terrestrial: Metanephros—adapted to different osmoregulatory demands.

Question 33

what does the central nervous system and the peripheral nervous system involve?

Answer 33

* CNS (brain/spinal cord), PNS (nerves and ganglia).

Question 34

what fish have a 3rd parietal eye and what is it linked to?

Answer 34

jawless fish, tuatara - linked to circadian rhythms and hormonal rhythms

Question 35

what group of mammals have electroreceptors?

Answer 35

evolved independently in monotremes (nerve endings in ‘beak’, not neuromasts)e.g. Echidna

Question 36

what is the Expensive Tissue Hypothesis? (Kotrschal et al., 2015).

Answer 36

Large brains come at cost of smaller guts & slower growth in guppies. supports trade-offs in brain evolution being such high energy demanding The selection lines showed a 9% increase in brain size in large-brained individuals, accompanied by an 8% smaller gut in females and a 20% smaller gut in males

Question 37

what does the expensive tissue hypothesis explain with humans?

Answer 37

why humans have relatively small guts compared to other primates while maintaining high brain metabolic demands

Question 38

what is the difference in physiology in aquatic vs terrestrial life?

Answer 38

* Aquatic: Fusiform body (movement), gills (O2 absorbtion), scales (H2O waterproof), single circulation with 2-3 chambered heart. * Terrestrial: Limbs, lungs, thick skin (epidermis), double circulation with 3-4 chambered heart.

Question 39

What is the life cycle of Eels?

Answer 39

Eggs – preleptocephalus larvae – leptocephalus – glass eels – yellow eel – silver eel – mature eel

Question 40

what are eels reproduction strategy?

Answer 40

Migrate to ocean to spawn, die post-reproduction (Diadromous & semelparous).

Question 41

what adaptations do eels have?

Answer 41

o Glass eels: Transparent, nocturnal (antipredatory). o Cutaneous respiration, torpor. o Have ventral lateral gill slits rather than internal gill chambers o Leaf-like larvae (leptocephali): Drift via currents.

Question 42

how is global change affecting eels populations (collapse)?

Answer 42

- Pollution (easily accumulated due to their high-lipid content), - overfishing (impacting all life stages) - habitat loss (reducing available spawning grounds and increased mortality) - climate disruption (affecting larval survival and drift), - parasites (Anguillicola crassus, a parasitic nematode that affects spawning) (Drouineau et al., 2018; Jacoby et al., 2015).

Question 43

what are the embryonic stages in a vertebrate

Answer 43

1. Zygote → Blastula → Gastrula. 2. Neurulation: Notochord, nerve cord. 3. Taxon-specific traits emerge (e.g., kidney types, limb morphology).

Question 44

what are the post-natal differences in fish/amphibians, reptiles and birds/mammals?

Answer 44

* Fish/Amphibians: Metamorphosis (larvae, juvenile, adult), indeterminate growth. * Reptiles: Hatch as mini-adults, intermediate growth in most species excl iguanas. Lay eggs in sand and sex is temperature determined (affected by climate change – skewed sex ratios). * Birds/Mammals: o Altricial: Helpless, high parental care. o Precocial: Independent at birth.

Question 45

what did Metcalfe and Monaghan (2001) find about early growth being crucial for life history?

Answer 45

found organ development and cell numbers can be reduced, diminishing fitness in adulthood.

Question 46

what is compensatory growth?

Answer 46

Fast post-deprivation growth can restore size

Question 47

what was found with Brown tree frog tadpoles with compensatory growth (Hector et al., 2012)

Answer 47

Brown Tree Frog tadpoles grew faster upon refeeding and grew larger than control however larval period extended by 5 days and swimming speed was negatively impacted by early nutrition restriction. However, post metamorphic traits e.g. hopping ability were enhanced going against the concept

Question 48

what are the trade-offs with compensatory growth?

Answer 48

Trade-offs with fitness include reduced immune function (increased susceptibility to disease and oxidative stress - Metcalfe & Monaghan, 2001), longevity (Orizaola et al., 2014) and reproductive costs (reduced success) Metcalfe & Monaghan, 2001.

Question 49

How is growth socially regulated? provide the examples of Clownfish and meerkats.

Answer 49

* Clownfish: Rank-based size control; growth suppressed to avoid conflict with dominants and subordinates (female is largest, them dominant male then subordinates) (Buston, 2003). * Meerkats: Subordinates grow in response to rivals’ size; dominance triggers growth bursts 2 months following their dominance (Huchard et al., 2016).

Question 50

how is song development in birds affected by early development?

Answer 50

* Dippers: Better-fed nestlings produce more complex songs; supports developmental stress hypothesis (conditions experienced during early development, particularly during nestling stages, can impact the quality and quantity of song produced in adulthood) (Magoolagan et al., 2018).