The Wonderful Net: How Camels and Penguins Are So Chill

Now let’s consider the adaptations of modern camels to a life in the harsh extremes of the desert. The most obvious adaptations are the humps, large fat deposits, which the camel can withdraw water from when food and drink are scarce. When they do find it, camels are capable of drinking water very quickly, with some sources indicating as many as thirty gallons in thirteen minutes! Their thick lips allow the animal to go after any vegetation it comes across, including hardy desert plants that are equipped with all sorts of large spikes and thorns. Thick, luscious eyelashes help to block the blowing sand from their eyes, and they can seal off their nostrils to prevent sand from getting in their, as well.* Their feet are broad, equipped with fleshy footpads that help distribute the weight of the camel over a broader surface area, just like a snowshoe.

Dromedary camels Camelus dromedarius in the Sahara Desert in Morocco, a comparison of four ungulate legs, a horse Equus sp., white tailed deer Odocoileus virginianus, fossil camel Paleolama, extinct bison Bison antiquus Photo Credit Zack Neher

A number of camel adaptations.  On the top left and bottom right, check out the luscious eyelashes and the thick lips.  On the bottom left, we have a comparison of four different species of ungulate.  From left to right, we have a horse (Equus sp.), a white-tailed deer (Odocoileus virginianus), an extinct camel (Paleolama), and an extinct bison (Bison antiquus).  Compare the skinny camel foot bones with the enormous, spreading foot in the picture on the top right.  Large, fleshy pads allow the camel to distribute its weight over a larger surface area.

While doing research for this blog post, I stumbled across two words that quickly caused this simple post on camels to spiral into a three part extravaganza: “rete mirabile.” Rete mirabile is Latin for “wonderful net,” and refers to a network of veins and arteries that are in close contact to one another. The close proximity of the different blood vessels allows heat to transfer from one to the other, in a process known as countercurrent heat exchange.

A diagram of a wonderful net rete mirabile counter current heat exchange by Zack Neher

A diagram of a rete mirabile, explained in the paragraph below.

What’s the point of the rete mirabile, or countercurrent heat exchange? A number of warm-blooded animals have some sort of “wonderful net” at work in their bodies, and it aids in thermoregulation. I first came across the term a few years ago while reading Daniel Ksepka’s blog on fossil penguins. Most penguins swim in waters that are colder than their body temperature, and since penguins are birds and birds are warm-blooded, that can be a problem. The large surface area and the low volume of the flipper means that it’ll lose heat to the environment fairly rapidly, faster than the rest of the body. As warm, oxygenated blood is pumped out of the heart and into the wing, the blood immediately begins to cool. The blood, now cold, is then pumped back into the body of the penguin. To help keep the flippers warm, the hot, outgoing blood vessels are in close proximity to the colder, incoming blood vessels. As the blood passes through, some of the heat from the outgoing blood is transferred to the colder blood returning from the flipper to the body of the bird. This ensures that the overall temperature of the flipper doesn’t drop too low, and means that the blood returning to the heart is warmed slightly. The flipper can remain colder, while the core body temperature of the penguin can remain stable.**

A trio of African Penguins Spheniscus demersus on the beach at Simon's Town in Cape Town South Africa with Michael Collett and Teddy Castro Photo Credit Zack Neher

A trio of African penguins (Spheniscus demersus) at Simon’s Town near Cape Town, South Africa.  Hidden within their flippers are rete mirabile, that help keep their core temperature warm.

Turns out, the rete mirabile is a pretty common occurrence, and it seems to crop up all over the place, especially in diving and burrowing mammals, both of which tend to suffer from a lack of oxygen. Some studies suggest that allowing the temperature of the limbs to cool means that they need less oxygen anyways, which is of further benefit for these divers and burrowers. Seals and sea lions have them in their flippers, and they can be found in the tails of whales, as well. In 2015, it was discovered that the opah, a large species of sunfish, employ the use of rete mirabile in their gills to help keep their heart warmer than the surrounding water temperature. Arboreal animals, or animals that live in trees, are sometimes found with these wonderful nets, as well, where they are called “vascular bundles.” Some scientists believe that the presence of these bundles is to reduce oxygen consumption in clinging animals, like sloths, pottos, the slow loris, and tree anteaters. They suggest that, since these clinging animals are flexing their muscles (which can restrict bloodflow), the lowered limb temperatures means that less blood flow is required altogether (O’Dea, 1989).  Another fascinating example of a mammalian rete mirabile is in the neck of the giraffe. To prevent the blood vessels in the head of a giraffe from bursting when the animal lowers its head below its heart to drink, the blood vessels in the rete mirabile expand, decreasing the pressure of the blood entering the brain!

A giraffe Giraffa camelopardalis in Kruger National Park in South Africa Photo Credit Zack Neher

A giraffe (Giraffa camelopardalis) in Kruger National Park, South Africa.  To help keep the bloodvessels in the head from bursting when the animal bends down to drink, the giraffe has a rete mirabile in its neck that expand to accommodate the extra blood.

In my research on camels, I was initially surprised to discover that they possess a rete mirabile in their heads. My experience thus far had usually found rete mirabile associated with warm-blooded animals that needed to warm up, but never with warm-blooded animals that needed to cool down! Of course, the temperature of the blood in the blood vessels of the rete mirabile is all relative. In the cold waters off the shores of South Africa, the blood of the African penguin will of course be warmer than its surroundings. But in the scorching heat of the Sahara Desert, the blood of the camel might actually be cooler than the surrounding air temperature! Studies indicate that the rete mirabile in the heads of camels might serve to help decrease the temperature of the brain, allowing it to function in the deadly heat of the desert. More research suggests that a number of birds and mammals actually have some sort of rete mirabile in their heads to help cool the brain, including a number of large migratory seabirds, such as boobys and albatross in the Hawaiian Islands and Midway Atoll (watch for them in an upcoming blog post!).

A black footed albatross Phoebastria nigripes soars gracefully above the waves in the Pacific Ocean between Ensenada, Mexico and Honolulu, Hawaii Photo Credit Zack Neher

A black-footed albatross (Phoebastria nigripes) soars over the waves in the Pacific Ocean, between Mexico and Hawaii.  Like camels, as well as many other seabirds, albatross possess a rete mirabile in their head to help cool their brain.


*After spending just one night in the Sahara Desert, I can confirm Anakin Skywalker’s gripe about sand getting everywhere. It really does. Even after several showers, I was still picking sand out of my hair, ears, and nose for about a week. Even a month and a half later, I still have some sand stuck in my iPhone case.

**This counter-current heat exchange can be used in industry and man-made machines, as well. For example, aircraft sometimes will use heat generated in one part of the machine to heat cold fuel.


Introducing “The Natural World: Connections”

On June 27th, 2012, I posted for the very first time on my original blog, The Natural World.  I was going into my senior year of high school, and was very eager to talk about dinosaurs and other animals on the World Wide Web.  It’s been almost four years now since I first started that blog, and I’ve changed a lot (at least I keep telling myself I have).  Last year, I decided to try and go through the several hundred blog posts I had posted and attempt to bring them up to date, both with any recent scientific advances, but also with a greater sense of academic rigor.  This task was daunting, to say the least, and difficult to do.  I was essentially rewriting posts that I no longer had a great deal of interest in, which kept me from trying to create new and interesting posts that were more relevant to my life today.  My friends suggested starting over, and the idea of a fresh start definitely appealed to me, so here we are.  I’m changing the name of my old blog to “The Natural World: Archives,” and this new blog is “The Natural World: Connections.”*  I’m really looking forward to being able to take advantage of the exciting features that WordPress has to offer, and I think I’ll be able to offer up a better system of picture viewing, as well.


The new blog, replete with a brand new blog logo.  Over the next few weeks, I’ll probably start explaining where some of the images in the logo actually came from.

The main focus of the blog has not changed, I still aim to promote fun and educational natural history reading.  However, the scope of my topics has definitely broadened, and some posts may be a little more off topic than others.  From everything that I’ve ever learned about learning, I believe that making connections is one of the best ways to learn about something new.  If you can connect a topic to something that you understand better, it will take less time and energy to understand.  It’s with these ideas in mind that I’m going to haphazardly construct my posts.

I have just returned from the study abroad program “Semester at Sea,” where we got to visit a number of different countries around the world, and make some amazing friends in the process.  For this introduction post, I thought I would share a few of the pictures that I got over the last four months, more or less in order.

Real talks in the Pacific Ocean with Michael Collett Photo Credit Zack Neher

Crossing the majestic Pacific Ocean.  It was easy to sit out on deck and watch the waves for hours.  During the Pacific crossing, we were able to spot a number of different seabirds, including several species of albatross and booby, several whales, a number of dolphins, flying fish, and believe it or not, a random owl an entire day out from Japan (and yes, I do have the photos to prove it).

Sunset on the Pacific Ocean Photo Credit Zack Neher

Sunrise on the Pacific.

Glorious Mt. Fuji as viewed from a road along the bus route in Hakone with Michael Collett Lacey Gasaway and Michael Sharp Photo Credit Zack Neher

Our first foreign stop was Japan.  On day three, I went with a few of my friends to Hakone to try and see the stratovolcano Mount Fuji.  We got really lucky, and fortunately it was a pretty clear day.

Zack Neher on a boat in Ha Long Bay in Vietnam Photo Credit Sonia Szeton

In Vietnam, I got the opportunity to check out the fascinating karst landscape of Ha Long Bay.

Michael Collett and Zack Neher in Munnar in Kerala in India Photo Credit Teddy Castro

In India, our group and I stayed in the southern state of Kerala the entire time, and we spent most of our time in local national parks and nature reserves.  Here is me with my buddy Michael Collett near the beautiful town of Munnar.

Two ships of the Indian Navy, the research vessel A74 INS Sagardhwani and the Sukanya class offshore patrol vessel P53 INS Savitri, pass each other in the waters of Cochi or Cochin in Kerala India Photo Credit Zack Neher

Our ship, the MV World Odyssey, was docked in Cochin, which is also the location of the Southern Naval Command of the Indian Navy.  As such, we got the opportunity to spot a number of the Navy’s ships steaming through, sometimes even conducting exercises.  In this photograph, we have the INS Sagardhwani (A74) on the left, and the Sukanya class offshore patrol vessel INS Savitri (P53) on the right.

An Olive Ridley sea turtle Lepidochelys olivacea in the Indian Ocean Photo Credit Zack Neher

For the most part, the seas were very calm between India and Mauritius, and by spending a lot of time out on deck, I was able to see some pretty exciting animals!  I’m fairly confident that this is an olive ridley sea turtle (Lepidochelys olivacea), based on the asymmetry of the costal scutes on the back of the animal.

The gang after snorkeling in Mauritius from left to right Teddy Castro Kim Kassander Mark Oldani Meghan with an H Adams and Zack Neher

Mauritius was a refueling and resupplying stop for us, and we only spent one day on land.  I was in a Field Lab (each class you take has one full-day field lab associated with it) for my Marine Biology class, and we got to go snorkeling!  This is me with a few of my friends, as we wait in line to get back on the ship.  From left to right, we have Teddy Castro, Kim Kassander, my roommate Mark Oldani, Meghan (with an “H”) Adams, and myself.

The Mountains of Mauritius seen behind the funnel of the MV World Odysseys Deutschland Semester at Sea Photo Credit Zack Neher

A few of the mountains of Mauritius from the top deck of our ship, the MV World Odyssey (or the MS Deutschland for you German fans of Das Traumschiff).  Until recently, Mauritius was the only home of the flightless pigeon-cousin, the dodo.

A pair of long beaked common dolphins Delphinus capensis porpoising in the waters two days out from Cape Town in South Africa Indian Ocean Photo Credit Zack Neher

Dolphins are not my specialty (and neither are sea turtles), but with the help of the Internet and the interpretive labels at the Iziko South African Museum, I have identified this dolphin as a long-beaked common dolphin (Delphinus capensis).  In the days leading up to our arrival in Cape Town, South Africa, the marine life became increasingly more abundant.  For the first time since we departed Mexico, we were able to see seals, and we also spotted several enormous pods of dolphins, a very high concentration of seabirds, and even two sharks!

Zack Neher at the Iziko South African Museum in Cape Town in front of the mounted skeletons of the spinosaur theropod Suchomimus and the juvenile sauropod dinosaur Jobaria

Here I am at the Iziko South African Museum in Cape Town.  They had a fantastic exhibit on paleontology, focusing a lot on the local Permian Karoo fauna.  They had some dinosaur fossils as well, including these mounted casts of the spinosaur Suchomimus attacking a juvenile Jobaria, a type of sauropod, long-necked dinosaur.

Zack Neher in Kruger National Park South Africa

I was also fortunate enough to be able to fly to Kruger National Park and take a safari, which was an experience that I had wanted to do since childhood.  Unfortunately, I got very ill the night before the full-day safari, but modern medicine saved the day, and I was able to lean against the back window thing and have some fun.

Baby African elephnat Loxodonta africana in the wilds of Kruger National Park South Africa Photo Credit Zack Neher

Here is a baby African elephant (Loxodonta africana) in Kruger.  Unfortunately, elephant overpopulation has become a real issue in the park.

Zack Neher and Michael Collett on top of Table Mountain National Park in the Cape Floral Kingdom in Cape Town South Africa Photo Credit Zack Neher

My buddy Michael Collett and I on top of of Table Mountain in Cape Town.  Table Mountain National Park is home to the Cape Floral Region, one of six of the world’s floral kingdoms.

A trio of African Penguins Spheniscus demersus on the beach at Simon's Town in Cape Town South Africa with Michael Collett and Teddy Castro Photo Credit Zack Neher

I wasn’t about to leave South Africa without getting my first chance to see penguins in the wild, even if it meant getting back to the ship late (a possibility that, for a period of time, we thought might be reality).  We got lucky, and were able to see a number of African penguins (Spheniscus demersus) relaxing on land in Simon’s Town.

A view of the tropical rainforest in the Kakum National Park in Ghana from the top of a treehouse with Michael Collett and Caleb LarnerdPhoto Credit Zack Neher

Our next stop was Ghana, where we spent our first night in a treehouse in Kakum National Park.  We got to do the canopy walk early in the morning, which was an amazing experience as well.

Caleb Larnerd Haley Collins and Zack Neher in the Shai Hills Resource Reserve in Ghana

My friends Cal Larnerd and Haley Collins and I visit the Shai Hills Resource Reserve in Ghana, where we had a guide who worked at the park drive around with us in the taxi (on the right is our taxi driver, Yaw).

Sand dunes in the Sahara Desert with Kim Kassander Michael Collett Meredith Leung Haley Collins Emily Kaplan Photo Credit Zack Neher

In Morocco, we spent a very long time on bus rides to get to the Sahara Desert.  It was pretty crazy to think that just a week and a half before, we had been in a rainforest.

The infamous Loch Ness near Inverness in Scotland United Kingdom Photo Credit Zack Neher

Before I went home to Colorado, I spent a few days in England, Ireland, and Scotland.  Here’s a picture of the famous Loch Ness.  Unfortunately, I saw no sign of the Loch Ness Monster.


This is just a few brief snapshots of what I’ve been up to the last few months.  I’ve got a big summer planned and there’s a lot to do, so stay tuned for some exciting content coming up soon!