Graduate Research Course
Reptile Biophysics & Biochemistry
Snakes, lizards, turtles, crocodilians β 11 000+ species of ectothermic sauropsids spanning 320 million years of evolution. Scales, venom, thermoregulation, and the physics of limbless locomotion.
About This Course
Reptiles include the sauropsid descendants outside the avian clade β or, more honestly, birds are reptiles and the paraphyletic label persists by tradition. The group is diverse: a saltwater crocodile (Crocodylus porosus) bites with 16 000 N, higher than any other extant animal measured; a gecko climbs glass using van der Waals forces at 500 000 setae per square cm; a sidewinder rattlesnake moves across Sahara sand at efficiencies no legged animal matches; and a king cobraβs 7Β mL of venom contains enough Ξ±-neurotoxin to kill an elephant. This course treats the physics, chemistry, and ecology of this ancient lineage.
Cross-links: Comp Sensory M7: Thermoreception,Climate M11 Deserts,Predators,Biochemistry,Avian (birds-as-reptiles).
Key Equations
Ectotherm Q10 Metabolic Law
\( R(T) = R_0\,Q_{10}^{(T-T_0)/10} \)
Heat Balance for Basking
\( M = k\,(T_b - T_a) + Q_{solar}(\theta) \)
Snake Friction Anisotropy
\( \mu_\parallel \neq \mu_\perp \Rightarrow v_{net} \neq 0 \)
Gecko Van-der-Waals Adhesion
\( F_{vdW} = \frac{A_H R}{6 D^2}\ \text{per spatula} \)
TSD Pivot Temperature
\( P_{male} = \frac{1}{1+e^{(T-T_{piv})/s}} \)
Croc Bite Lever
\( F_{bite} = F_{muscle}\,d_m/d_b \)
Nine Modules
M0
Evolution & Phylogeny
Sauropsida vs. Synapsida split 320 Mya, modern clades (Testudines, Squamata, Rhynchocephalia, Crocodylia), birds-as-reptiles nesting, Mesozoic radiation, paraphyly debate.
M1
Scales, Skin & Ecdysis
Ξ²-keratin vs. Ξ±-keratin, scale morphogenesis reaction-diffusion, ecdysis biochemistry (ecdysozoan molt origins), gecko van der Waals setae, shed-skin whole vs. flake.
M2
Ectothermy & Thermoregulation
Behavioral heliothermy, basking costs, set-point thermoregulation, Q10 metabolic scaling, Huey-Stevenson 1979 operative temp, gigantotherm crocodile mass inertia.
M3
Snake Locomotion
Four gaits: lateral undulation, concertina, rectilinear, sidewinding (Jayne 1986), belly-scale friction anisotropy, Socotran egg-eating, arboreal cantilever limits.
M4
Sensing: Jacobson, IR, UV
Bifid tongue β Jacobson organ (vomeronasal) tropotaxis, pit-viper loreal IR organ TRPA1 (Gracheva 2010), lizard parietal eye UV-photon dosimetry, snake vision.
M5
Venom Biochemistry
Elapid Ξ±-neurotoxins blocking nAChR vs. viperid hemotoxins (SVMPs, SVSPs), three-finger toxins, PLA2, Toxicofera convergence (Fry 2006), antivenom production.
M6
Reproduction, TSD & Parthenogenesis
Temperature-dependent sex determination (TSD) in turtles + crocodilians, climate pivot-temp risk (Janzen 1994), whiptail parthenogenesis Cnemidophorus, matrotrophy.
M7
Crocodilian Biology
Bite force 16 000 N saltwater croc (Erickson 2012), 4-chambered heart, parental jaw-brooding, pressure-sensitive dermal sensors, tooth replacement 50Γ lifetime, gharial diet.
M8
Conservation & Climate
Snake fungal disease Ophidiomyces, sea-turtle TSD under warming, lizard Sinervo 2010 extinction predictions, IUCN Red List, pet trade, illegal reptile markets.