Welcome back to Nature League!

One of my favorite things to do on Nature League is to interact with you on Twitter,. Facebook, and in the comments section below.

I recently asked you to send me questions about life on Earth, Nature League, and me, and you guys did not disappoint! So without further ado, let's do some Q and A! [CHEERY INTRO MUSIC]. Do you still study?

I do still study! At present, I'm working on finishing my PhD in wildlife biology, focusing on international biodiversity conservation. Over the last two years, I've gotten really interested in environmental philosophy as well, and I've taken some courses on that topic.

Both biodiversity conservation and philosophy topics within the Anthropocene definitely factor into the topics I choose to cover on Nature League. If you could give humans one animal feature, what would it be and why? Fun fact!

Adrian and I have discussed this exact topic here on Nature League, and we even went next-level with it, complete with white board drawings. Definitely check out this video in the info card if you're down for an adventure. When was the first time you discovered sharks, and what made you fall in love with them?

I definitely had all kinds of shark toys growing up, but I think some of my first exposure was through animal books. I specifically remember having one on sharks, one on dinosaurs, and one on reptiles. I asked my parents about this, and they said there were a ton of simultaneous influences.

Not only did I love the shark exhibits at the Florida Museum of Natural History on campus at the University of Florida where I grew up, but apparently I was obsessed with the shark teeth and shark in jars trinkets at tourist traps on the beach... Go figure. My dad said that when I was 5 and we were at Sea World, I had a distinct desire to go see the sharks.

Not Shamu, but the sharks. That said, my dad followed up with this text, and I'm really hoping for sarcasm…. If you want to learn more about why I love sharks so much, you can check out an episode of the I Love It podcast with Matthew Gaydos where I talk all about that.

Link in the description below. When they say some birds can see more colors, do they see more detail within the spectrum we see, or are they seeing infrared or ultraviolet? Yay birds!

Great question. To the best of our knowledge, birds are able to see the entire UV to visible light spectrum, meaning everything within the rainbow we're familiar with, plus UV, or ultraviolet rays. Birds also have something called “tetrachromacy,” meaning “four colors.” Basically, they have an extra color receptor, or cone, in addition to the three receptors that humans have.

In some birds, this fourth cone allows them to see more of the UV spectrum, while in others it enhances their sensitivity to violet light. One of the coolest things I've seen in a while regarding this topic was the recent discovery that puffin beaks look like glow sticks when viewed under UV lights. Granted, the puffins have likely known this for a while, but it was a sweet discovery for human ornithologists.

How come it's possible to get a huge difference size-wise between dogs, whereas cats are roughly the same size? It would be pretty awesome to have a German Shepherd sized cat. It's all about selective pressure!

In the case of domestication, it's technically called “artificial selection”-- that's when humans pick and choose individuals to breed in order to perpetuate traits desirable by humans. In the case of domestic cats, they've remained relatively unchanged over time compared to domestic dogs, probably because humans haven't bred cats specifically for size, unlike dogs. That said, cats and humans have sort of co-domesticated each other...

So for all we know, cats are actually the ones doing the artificial selection around here! Dogs are domesticated by humans. Humans are domesticated by cats.

Cats inherit the earth. Except, ants actually. It's gonna be ants.

Human embryos have gill slits, and one of them develops into the ear bones (or something). What do the other gill slits grow into? Indeed!

As surprising as it might sound, human embryos absolutely have gill slits, though they aren't actual gills and don't develop into gills in humans. The scientific term for these embryonic structures is “pharyngeal pouches,” and in fish they do eventually push through to the outside of the body and include gill bars of bone or cartilage as well as the actual gill filaments. If you trace the developmental fate of those pharyngeal pouches and gill bars in a human embryo, you'll find some human structures you're probably more familiar with -- specifically, the cartilage in our throats, the small glands in our necks, and bones in the middle ear.

What's interesting is that these features in humans are very closely related to the gill arches of jawless fish, the jaws of jawed fish, and the jaws of reptiles. Sort of makes sense that our jaw articulates so closely to our ear…. But without real gills, I guess we'll just have to keep relying on gillyweed.

Since whales are mammals, do they have hair? Right! Where are all the whale hairs?!

Well, there are actually quite a few marine mammals still sporting hair. Seal and sea lions have a ton of hair, and manatees have some hair concentrated around their faces. However, hair is nearly absent in whales and dolphins, though they do have some.

We call these whale hairs “vibrissae”- that's the scientific terms for the bristles that we lump in with mammal hair. Whale hairs are generally found on their faces, blowholes, and tubercles. For dolphins, there is usually some hair on the face of their fetuses, though some research suggests that narwhals and beluga whales never have hairs, even in utero.

The hairs that whales do have are usually uneven over the body and concentrated in areas that are most likely to encounter some kind of stimulus. For example, in the bowhead whale, their chin is at the very front of their bodies and interacts with the oncoming environment more than other body regions. Lo and behold, bowhead whales have a high density of hairs on their chins.

Even though hair is a classic characteristic of mammals, there are even some land mammals that have either lost this trait or had it drastically reduced. For example, the naked mole rat is a mammal, and yet it has naked in its name! However, that species does have a few hairs that are highly specialized to help with sensing their environment, so they're more like “nearly naked except for awesome feeler hairs mole rats”.

Can you please make the noise that paleontologists think T. rex made? Well, the best guess of paleontologists right now is that T. rex sounded something like a goose or even crocodilian. So, um…(make noise).

How do pioneer plants grow with so little nutrients? Pioneer plants are species that arrive, survive, and thrive in ecosystems that have recently been disturbed or manipulated in some way. These ecosystems typically have less than ideal habitat, so pioneer plants have all kinds of special adaptations that allow them to thrive in these areas.

So for example, when Mount St. Helens went off in Washington state here in the U. S., lava and ash all kinds of things totally wiped out the area, so there was kind of nothing living there.

Then, plants started to pop up, and those first plant species are what we would refer to as pioneer plants. Most pioneer plants are especially resistant to drought and can easily disperse their seeds. Low soil development in these areas also means that there's a reduced nutrient supply for these species.

To make up for this, some pioneer plants have smaller seeds that contain smaller food reserves, and some have long roots or bacteria that help obtain nitrogen for the plant. What's cool about pioneer species in general is what happens next- a process called “ecological succession”. The presence of pioneer species and the consequences of their survival allow /other/ species to colonize the area and eventually leads to a completely new ecosystem.

What did fungi evolve from? Kingdom Fungi puzzled biologists for quite some time. Were they more closely related to animals?

Were they plants? The fossil record doesn't have much in the way of fungi, but scientists have found evidence of fungi within plant fossils, so we at least know they're old. At present, data suggest that fungi are more closely related to animals than plants, despite how they look.

And, current molecular data suggest that plants, animals, and fungi diverged from each other close to a billion years ago. Kingdom Fungi is monophyletic, which means that all present day fungi evolved from a single, common ancestor. Some research suggests that about 550 million years ago, land fungi split from a group called chytrids.

Chytrids are aquatic, so it's likely that fungi started in the water. We're learning more and more about kingdom Fungi all the time, so these ideas are likely to change as new evidence appears. That's what makes science fun!

How do we go about cataloging the vast biosphere living underground, in the rocks of the Earth? Are there projects in the works to do this? Oh man!

Underground, or subterranean, biodiversity is so important, but often overlooked when it comes to our conceptions about life on Earth. If you just consider continental Earth, 97% of liquid freshwater is actually below the surface, and the biodiversity in these systems is unique and incredible. Luckily, there are a lot of scientists and organizations that care about cataloging subterranean biodiversity.

In 2010, a European group released their first ever Atlas of Soil Biodiversity that came from a collaborative project aimed specifically at understanding life in the soil. International projects like the Catalogue of Life include subterranean species, and the third edition of the Encyclopedia of Caves just out this year has an entire chapter dedicated to mapping subterranean biodiversity. How old is water?

The planet Earth is estimated to be about 4 and a half billion years old, and the Earth's oceans are almost as old as that. Way back when, Earth would have been two hot for liquid water, so one possibility as to how the oceans got here is that as the Earth cooled, water vapor condensed into liquid form. Another theory is that ice was delivered from space by comets or meteors, and then melted.

Yet another, more recent theory is that some of Earth's current water came from dust particles deep inside Earth that were soaked with water. However it got here, the water on Earth is probably close to 4 billion years old, and that means that it's been recycled quite a bit. Humans haven't been around long enough to have completely gone through and recycled.

Earth water, but dinosaur just might have. The reign of dinosaurs was about 186 million years long, so if you want to talk about your drinking water having come from another body, you might want to start thinking Tyrannosaurus rex instead of Homo sapiens. I absolutely love thinking about and answering the questions you send me both in the comments section and on social media.

Despite being obsessed with life on Earth, there's still a ton of things I don't know about it, plus, scientific consensus is constantly changing with new data. So keep your questions coming so we can keep learning together- I deeply appreciate it and always look forward to getting familiar with something new. Thank you so much for your questions, and if you'd like to continue going on life on Earth adventures with us here on Nature League, go to youtube.com/natureleague, subscribe, and share.