1. Conservation and Ecology of Marine Reptiles
MARE 494
Dr. Turner
Summer 2006

2. Thermo & Osmo Regulation
Live in unique marine media that causes problems with thermal biology and regulation of salt & water
Like other marine animals have adaptations which allow for survival

3. Thermal Biology
Ultimately tied to thermal constraints of their environment
Sea turtles are unusual among reptiles – large body size allow adults to use insulation & blood flow to alter (control) body temperature (Tb)
Large difference in thermal patterns among hatchlings, juveniles, & adults

4. Thermal Biology ??? Conformer: Physiological state = environment
Regulator: Physiological state different from environment
Conformer
Body Temp
Regulator
Ambient Temp
???

5. Heat Exchange

6. Lets Get Biophysical Energy exchange controls the TB of sea turtle
Chemical energy drives metabolism & provides and internal heat source
Energy from the environment is main source of heat for sea turtles (land or sea) except for very large animals

7. Surf & Turf
In water thermal radiation absorbed near surface – heat exchange is by:
Conduction
Convection
On land heat energy exchange is by:
Radiation
Evaporation

8. Energy Balance Equations
Qabs + M = R + C + E + G
Qabs = radiation absorbed by the surface of the animal from the sun
M = metabolic heat production
R = thermal heat emitted by surface of the animal
C = heat energy lost by convection
E = heat energy lost by evaporation/gained by condensation
G = heat energy lost or gained by conduction through direct contact with soil, water, or substrate
HEAT IN = HEAT OUT + HEAT STORED

9. Land!
Sea turtles nest at night because exposure to the hot sun during the day would lead to lethal heat gain
Gradient across thickness of carapace & plastron causes internal heat lag between surface & deep body
However, deep body it not great enough heat sink to sustain but a few degrees ambient temperature increases

10. Basking! Sea turtles bask on land & in water
Turtles that bask on land typically seek out beaches facing outer reefs and prevailing trade winds
Lower temps than on beaches on opposite side of Island
Do we see this in practice?
Punalu‘u versus Kona

11. Regulate to Regulate
How do basking turtles regulate internal temperatures?
Flip sand onto flippers & carapace
reduce surface temperature > 10°C
Flipper into water
reduce surface temperature > 10°C+

12. Cold-Stunned Occurs when temperatures drop below 8°C
Lose ability to swim & dive, buoyancy control, float to surface, & die
Probably disruption of metabolic pathways

13. Thermoregulation? Are leatherback sea turtles homeothermic?
Metabolic rate higher than cheloniids; higher than typical reptile scaled to its size
Still ½ the metabolic rate of mammals
May allow enough for these large turtles to function at very cold temperatures during deep diving bouts – oceanic existence

14. Tag’em & Bag’em
“Since they stopped testing on animals, a guy like me can really clean up!” – Barney Gumble

15. Osmoregulation? Are leatherback sea turtles homeothermic?
Metabolic rate higher than cheloniids; higher than typical reptile scaled to its size
Still ½ the metabolic rate of mammals
May allow enough for these large turtles to function at very cold temperatures during deep diving bouts – oceanic existence

16. Coping with Salinity
“Yaarh! I hate the sea and everything in it” - Captain Horatio McCallister
Some molluscs

17. Osmo Kramer
“These pretzels are making me thirsty!” – Kosmo Kramer
Sea turtles live in medium that is almost 3X more concentrated than body fluids
Some ions greater – 23X Mg2+
Must maintain internal osmotic & ionic homeostatis

18. Salt!
Salt Concentration

19. Reptile Profile
Respiration not a major source of water loss in marine reptiles
Water loss function of permeability of transcutaneous osmotic gradient
Water loss via urine & feces (cloaca) low

20. Na+Na+Na+Na+, HeyHeyHey, Goodbye
Na+ efflux at similar levels to marine elsambranchs (lower than teleosts)
Sea turtles have low epithelia permeability for Na+
Bulk of salt loss is from salt gland
60% in loggerhead
90% in green

21. Salt Ingestion Ingestion major source in salt intake
Esophagus provides protection against incidental drinking – papillae & sphincter
help to “trap” food; expel water

22. Glands! Reptiles have a unique variety of organs used as salt glands
Salivary glands – sea snakes
Lingual glands – crocodiles
Nasal glands – lizards
Lachrymal gland – sea turtles
2X size of leatherback brain

23. Salt Gland Powers, Activate
“Brian, take out your ring. Wonder Twin powers activate. Shape of steam.” "Peter, we got these from a box of fruit loops” – Peter & Brian Griffin
When actived - discharges a fluid
6X that of blood; 2X seawater
When inactive – ¼ the concentrating capability
Greater than marine birds; 2X shark rectal gland
Unlike avian glands – remove Mg2+

24. Salt Gland vs. Kidney