School of Life Sciences | Ask A Biologist

Why is Rudolp's nose red?

The Earth’s carrying capacity is the number of people the Earth can support without using resources faster than the planet can reproduce them. Experts disagree on this number because carrying capacity depends on a variety of factors including: the type and quantity of available resources, how these resources are distributed, how much of the resources each person uses, and the people’s relative quality of life. Read more about carrying capacity at the Encyclopedia of Earth.

Grade Level: 12

Have a different answer or more to add to this one? Send it to us.

That's a great question. Most bony fish have something called a swim bladder inside them. This is basically an inflatable bag. Fish use the swim bladder to control their buoyancy by inflating it with oxygen from their gills using a gland called a gas gland. This increases their volume and pushes them towards the surface of the water. Some fish, however, have a tube that runs from their swim bladder to their gut, and they gulp air from the surface and push this into the bladder. Most of these fish live in murky, muddy waters that are low in oxygen content.

Question From: Gerett
Grade Level: 8

Have a different answer or more to add to this one? Send it to us.

Each gull species has its own vocabulary of sounds, and they communicate things such as mating rituals, warning calls, and location of food sources. Young gulls have high pitched whining calls that together with their behavior cause parents to regurgitate food for them. Most warning calls are growling-like. Some calls are soft and others are loud and far reaching to warn away competitors. You may be watching and listening to several species of gulls, and each species may have sounds peculiar to its species (such as mate attraction calls).

Question From: Susan
Grade Level: 10

To learn more about the songs of birds, try these links.

Have a different answer or more to add to this one? Send it to us.

It is hard to connect "smarts" intelligence with brain size differences in animals. In some cases it is possible to judge intelligence and brain size, like if we were to compare a frog brain and a cat brain. However, when you compare the brains of the same animal species you run into problems. So it is difficult to connect brain size and intelligence when you compare one cat with another cat or a human to another human.

Something for you to think about: Elephants have a much larger brain than humans. Are elephants smarter than us?

Question From: Katie
Grade Level: 8

To learn more about the brain, try these links.

Have a different answer or more to add to this one? Send it to us.

Top Questions

Top Question Header Graphic

Have you ever wondered what  questions we have received and answered over the years? You are not alone. Others have wondered the same thing. After answering more than 30,000 queries we have sorted through our collection and are listing a few of our top questions and answers.

We hope you enjoy them.

Sabine Test Page

Sabine Test Page

You are missing some Flash content that should appear here! Perhaps your browser cannot display it, or maybe it did not initialize correctly.

Here is a bat!

Catch and Sketch Plankton

collection image

Catch and Sketch Plankton

By Colleen Miks
Illustrated by James Baxter

show/hide words to know

  • Microscopic: too small to be seen with an unaided eye.
  • Organism: a living thing that can be small like bacteria or large like an elephant.
  • Plankton: a group of free floating organisms living in water that includes many kinds of plants and animals... more
  • Realistic: to draw, paint, or sculpt an object in great detail so that it looks like the object.
  • Scale Bar: a line drawn and placed along side an object or on a map to indicate the true size of the object or area of the map.

Sometimes when we only look at a plant or animal we miss seeing some of their amazing parts and how they are constructed. The story of the Invisible Watery World shows that there are tiny living things that come in many shapes and sizes. In lakes, streams and oceans there are plankton. These are small and often microscopic organisms.


Ask A Biologist Logo

Link: content/robert-hooke

From: July 21, 2013 at 06 hours
To: July 29, 2013 at 06 hours

From: July 21, 2013 at 06 hours
To: July 29, 2013 at 06 hours

From: July 21, 2014 at 06 hours
To: July 29, 2014 at 06 hours

From: July 21, 2015 at 06 hours
To: July 29, 2015 at 06 hours

From: July 21, 2016 at 06 hours
To: July 29, 2016 at 06 hours

From: July 21, 2017 at 06 hours
To: July 29, 2017 at 06 hours

From: July 21, 2018 at 06 hours
To: July 29, 2018 at 06 hours

From: July 21, 2019 at 06 hours
To: July 29, 2019 at 06 hours

From: July 21, 2020 at 06 hours
To: July 29, 2020 at 06 hours

Share to Google Classroom

dropdown arrow downdropdown arrow up  Learn More

Share to Google Classroom