to get warmth from his environment.

Sup meatbags, Trace here for DNews to talk about why you're all SO HOT. But really, you're

hot. Have you ever thought about why? Thermoregulation. Science divides thermoregulation into endothermic

or ectothermic; homeothermic or poikilothermic (poiˈkēləˌTHərmic). Endo and ecto thermic

describe an animal that either makes it's own heat or gets it from the environment.

Homeo and Poikilo describe whether the temperature is constant.

A cute siamese cat is an endotherm and homeotherm, it makes it's own heat, and maintains a constant

body temperature; most mammals and birds are endothermic homeotherms -- what elementary

school would call warm-blooded. Fish, amphibians, reptiles and most invertebrates are ectothermic

poikilotherms; they get heat from the environment and let their body temperature fluctuate -- what

the youths would call cold-blooded. But that's only part of the picture! They make their

own heat, but don't always maintain it. Some fish maintain a constant temperature and create

heat by swimming from cold to warmer water, but can't generate it themselves; leatherback

turtles and lamnid sharks do this too! All I'm saying is, it's a wider world than the

black-and-white of cold versus warm blood!

But that's not all! Dinosaurs used to be thought of as cold-blooded terror lizards that would

obviously make AMAZING PARK ATTRACTIONS DON'T WORRY NOTHING COULD GO WRONG. // But a study

in Science found dinosaurs were likely mesotherms -- they used a combination of internal processes

and environmental factors to adjust their overall body temperature! Plus, animals that

hibernate like chipmunks and some bats are heterothermic! Whew. Yeah, It gets confusing,.

The reason we simplify it to warm and cold blooded is because temperature, which is mainly

circulated by the blood, affects things like muscle function and brain size. Colder muscles

react slower, meaning ectothermic animals have to behave sluggishly when the environment

is cooler. They have no choice! Even if a predator is around. According to Spring and

Holley's Introduction to Zoology, with a 18 degree F (10C) change in temperature, muscles

contract three times faster, pulling three times the power. Knowing this, you can understand

why yellowfin tuna evolved to be poikilotherms! Warmer muscles react better, allowing them

to keep their bodies at a slightly higher temperature than the surrounding water; thus

they maximize their power and catch prey.

Mammals and birds range in temperature from 97 to 104F (37-40C) and that has a cost; we

have to eat to live and regulate metabolism! Pandas spend 10 to 16 hours a day eating,

and the British Medical Journal recorded hunger strikers who lasted 40 days without food.

But that's child's play; pythons can go a year between meals. So why aren't we just

SLIGHTLY regulating our temperatures like tuna? Seems like a big waste to burn all that

energy and stay hot all the time, right?

All that heat keeps our muscles ready for action. Endothermic animals can almost always

outrun ectothermic animals; assuming they survive the initial strike. Ectothermic animals

are better at that initial attack… think a snake or fast-fish! Insects with cold muscles

can't fly, the Sphinx Moth vibrates its muscles before takeoff to get them warm. Plus, cold

animals may miss opportunities to use their muscles to get all up ons and mate! Warm-blooded

animals can mate ANYTIME. Which… you know. That's fun. PLUS all that energy and heat

allows for the evolution of more complex brain structures, which allowed me learn to talk

to you right now!

That being said, it's hot. It's real hot. And sometimes it's just TOO hot… or too

cold! So animals that evolved to be homeothermic -- maintaining temperature -- had to ALSO

evolve fur or blubber to stay warm and sweat glands or panting to cool off. But that's

a whole other video. Want to know why we sweat and how AWESOME we are at it? Check out this

video Do you have a science question you want us to answer? YouTube gave us the comments for a reason,

so y'all could troll, but you could ALSO use them to ask me a science question. Maybe try

that? And please subscribe! We're here every day for our subscribers, and I love my job.

So from the bottom of my heart, thanks!