The Western Interior Cretaceous Seaway

Between 70 and 100 million years ago, much of central North America was covered in a shallow, inland sea known as the Western Interior Cretaceous Seaway.  While the ancestors of Tyrannosaurus and Triceratops roamed the fragmented continent, an amazing array of fascinating marine reptiles prowled through the waves.  Sea turtles the size of a small car, long-necked plesiosaurs, and fifty foot long relatives of the Komodo dragon.  Check out the documentary by clicking on the link below!

The first stop in the documentary is to visit Dinosaur Ridge, a very exciting fossil site just a few minutes drive from where I live in Colorado.  Dinosaur Ridge has a number of very interesting points of geological and paleontological interest, but the portion of the ridge that we visit in the documentary are the fossil dinosaur trackways on the eastern side of the ridge.  Here, just before the area was completely inundated by the seaway, a number of different dinosaurs (paleontologists believe some sort of large, iguanodont-like ornithopod; an ostrich-like ornithomimosaur; and a large Acrocanthosaurus-like theropod) left their footprints in the once-squishy beach sand.  In other, nearby rock layers, we can find the remains of lithified ripple marks, showing exactly where the waves would lap gently at the shore.

Fossil dinosaur trackways preserved at Dinosaur Ridge in Colorado ornithopod theropod and ornithomimosaur tracks from the Early Cretaceous on the shores of the Western Interior Seaway Photo Credit Zack Neher

Fossil dinosaur trackways preserved at Dinosaur Ridge in Morrison, Colorado.  The majority of the footprints are thought to belong to some sort of ornithopod dinosaur like the famous Iguanodon, although some are attributed to an ornithomimosaur, and others to a large, Acrocanthosaurus-like theropod.  Crocodilian tracks are also reported.

Lithified petrified ripple marks from the shore of the ancient Western Interior Cretaceous Seaway preserved at Dinosaur Ridge in Colorado Photo Credit Zack Neher

Petrified ripple marks from the shore of the ancient Western Interior Cretaceous Seaway, preserved at Dinosaur Ridge.

Zoomed in lithified petrified ripple marks from the shore of the ancient Western Interior Cretaceous Seaway preserved at Dinosaur Ridge in Colorado Photo Credit Zack Neher

 

A mounted skeleton of the theropod dinosaur Acrocanthosaurus at the Houston Museum of Natural Science in Texas with Cian Kinderman Photo Credit Zack Neher

A mounted skeleton of the theropod dinosaur Acrocanthosaurus, on display at the Houston Museum of Natural Science in Texas.  This dinosaur gets its name from the enormous, elongate neural spines running down its back, which would have made the animal look much larger and more intimidating than a relative without them.

Next, I visited Doug Hartshorn, the Museum Coordinator at the Morrison Natural History Museum, so that he could tell us more about some of the Western Interior Seaway’s inhabitants.  He told us about the mosasaurs, such as Tylosaurus, and the Pteranodon, a species of pterosaur, a group of winged reptiles that were closely related to dinosaurs.

Mounted skeleton of the mosasaur Tylosaurus on display at the Houston Museum of Natural Science in Texas with Cian Kinderman Photo Credit Zack Neher

Mounted skeleton of the mosasaur Tylosaurus on display at the Houston Museum of Natural Science in Texas.  Tylosaurus and the other mosasaurs were not dinosaurs, and in fact were close cousins of modern day monitor lizards, such as the Komodo dragon (Varanus komodoensis).  In this shot, you have an excellent view of the pterygoid teeth, situated on the roof of the mouth of the animal.  These twin rows of teeth could be used like a conveyor belt, to pull prey back into the belly of the beast.

Zach Evens and Zack Neher for scale next to a mounted skull of the mosasaur Tylosaurus at the Morrison Natural History Museum in Colorado with Masaki Kleinkopf Photo Credit Mona Kamath

My friend Zach Evens and I next to the Tylosaurus skull at the Morrison Natural History Museum in Colorado.  Although Tylosaurus, one of the biggest members of the group, could grow up to fifty feet long, this is still much smaller than the monster-sized mosasaur featured in the movie “Jurassic World.”  Photo Credit: Mona Kamath

Mounted skeletons of the sea turtle Toxochelys and the mosasaur Plioplatecarpus on display at the Houston Museum of Natural Science in Texas with Cian Kinderman Photo Credit Zack Neher

Mounted skeletons of the sea turtle Toxochelys and the mosasaur Plioplatecarpus, on display at the Houston Museum of Natural Science in Texas.  Toxochelys, the most common sea turtle in the Western Interior Seaway, had evolved a bite that was perfectly adapted to consume hard-bodied prey, such as clams and ammonites.

Dumeril's monitor lizard Varanus dumerilii attacks a plastic Megalodon like in Jurassic World at the Morrison Natural History Museum in Colorado Photo Credit Zack Neher

Herkimer, the Dumeril’s monitor lizard (Varanus dumerilii) at the Morrison Museum attacks a plastic shark as he reenacts his favorite scene from Jurassic World.  Herkimer, like all monitor lizards, is a close relative of the mosasaurs.  The white dot on top of Herkimer’s head (just a little bit behind his eyes) is actually a third eye known as the pineal eye, something that we see on the skull of mosasaurs, as well.

Mounted skeleton of a female Pteranodon on display at the Morrison Natural History Museum in Colorado Photo Credit Zack Neher

Mounted skeleton of a Pteranodon, on display at the Morrison Museum.  Pteranodon is one of a group of flying reptiles called pterosaurs, closely related to dinosaurs and crocodilians.  There appear to be two different morphs of Pteranodon, those with a small crest on their head like that featured here, and those with larger crests, as in the photograph below.  In a classic case of sexual dimorphism, many paleontologists suspect the small-crest morph to be female, and the large-crest morph to be the male.

Masaki Kleinkopf next to a mounted skeleton of Pteranodon sternbergi on display at the Rocky Mountain Dinosaur Resource Center in Woodland Park, Colorado Photo Credit Zack Neher

The large-crest morph of Pteranodon, most likely the male, with my friend Masaki Kleinkopf for scale.  Scale is important for these animals, as many of them are a good deal larger than any flying animals we have alive today.  Modern albatross have the largest wingspan of any flying creature today, somewhere around eleven feet wide.  An good-sized Pteranodon would have a wingspan much wider than that, and some other pterosaurs grew even bigger still.  This cast is on display at the Rocky Mountain Dinosaur Resource Center in Woodland Park, Colorado.

After speaking with Doug for a bit, we briefly look at a few other animals that lived in the seaway.  I’ve included those images here, as well as several more fascinating creatures that I didn’t get the chance to cover in the documentary.

Zack Neher for scale with the famous Xiphactinus gillicus fish-within-a-fish Inception fossil on display at the Sternberg Museum of Natural History in Kansas Photo Credit Mark Neher

The famous “Fish-within-a-fish” Inception fossil, on display at the Sternberg Museum of Natural History in Kansas.  It appears that the larger fish, Xiphactinus, died shortly after ingesting a smaller species of fish, Gillicus. Photo Credit: Mark Neher

African dwarf clawed from Hymenochirus sp. after choking to death on some sort of algae eater Photo Credit Zack Neher

Although I always thought it a bit hard to swallow that the Xiphactinus choked to death on prey that was simply too large for it, a startling encounter with my pet African dwarf clawed frog (Hymenochirus sp.) a few years ago changed that.  Apparently, it had decide that going after the algae eater in the tank was a good idea, despite the fact that the algae eater was much larger than it could reasonably expect to handle!

The teeth of the prehistoric shark Cretoxyrhina on display at the Sternberg Museum of Natural History in Kansas with Mark Neher Photo Credit Zack Neher

The teeth of the prehistoric shark Cretoxyrhina on display at the Sternberg Museum in Kansas.  This shark is thought to resemble the modern great white shark (Carcharodon carcharias) in size and general shape.

Model of the ammonite Jeletzkytes on display at the Houston Museum of Natural Science in Texas with Cian Kinderman Photo Credit Zack Neher

This is a model of the ammonite Jeletzkytes on display at the Houston Museum.  This ammonite genus was one of many that inhabited the Western Interior Seaway.  Although ammonites resemble the modern genus Nautilus, they are only distantly related to one another.

Mona Kamath sitting on a specimen of Placenticeras meeki, a giant ammonite, at the Kremmling Cretaceous Ammonite Locality in Kremmling Colorado Photo Credit Zack Neher

Mona Kamath sitting on a specimen of Placenticeras meeki in the field at the Kremmling Cretaceous Ammonite Locality.  Placenticeras is a giant genus of ammonite, and are fairly abundant at the site.  To learn more about KCAL, check out this post from the The Natural World Archives, by guest blogger Wayne Itano.

Didymoceras cheyennensis ammonite attached to an Inoceramus simpsoni clam from North Dakota on display at the Mace Brown Museum of Natural History in South Carolina Photo Credit Zack Neher

The bizarre fossil shell of the ammonite species Didymoceras cheyennensis, attached to a specimen of the fossil clam Inoceramus simpsoni, on display at the Mace Brown Museum of Natural History in South Carolina.  In my opinion, Didymoceras is one of the most ridiculous and impractical animals that I can imagine.

Mounted skeletons of Archelon ischyros Elasmosaurus and other extinct sea monsters on display at the Black Hills Institute of Geological Research, Inc. in South Dakota with Mikaila Bloomfield Seamus Kieran and Emily Barber Photo Credit Zack Neher

Mounted skeletons of the giant sea turtle Archelon ischyros, the long-necked plesiosaur Elasmosaurus, and an assortment of other extinct sea monsters on display at the Black Hills Institute of Geological Research, Inc. in South Dakota.

Mounted skeleton of the enormous car-sized sea turtle Archelon ischyros on display at the Black Hills Institute of Geological Research, Inc. in South Dakota with Mikaila Bloomfield Seamus Kieran and Emily Barber Photo Credit Zack Neher

A closer shot of the enormous car-sized sea turtle Archelon ischyros.  Archelon is the largest species of sea turtle ever discovered, and is thought to be fairly closely related to the modern leatherback sea turtle (Dermochelys coriacea).

Mounted skeleton of the plesiosaur Elasmosaurus on display at the Black Hills Institute of Geological Research, Inc. in South Dakota with Mikaila Bloomfield Seamus Kieran and Emily Barber Photo Credit Zack Neher.jpg

The enormous and ridiculously elongate neck of the plesiosaur Elasmosaurus.  Reminiscent of the terrestrial sauropods, the heads of these creatures look almost comically small at the end of their necks, the length of which could vary considerably between different genera.

Despite the mountains and the mile-high elevation that we see today, it is always a startling reminder to come across a fossil seashell or shark tooth while out hiking and enjoying the Colorado outdoors.

The Flatirons and the Rocky Mountains covered by clouds in Boulder Colorado Photo Credit Zack Neher

 

Birds, Poop, and Naval Warfare: The Story of the Midway Atoll

At only two and a half square miles in area, the Midway Atoll is an excellent example of the famous phrase “size matters not.” Midway’s history also helped to fulfill the ancient prophecy of “bird poop will one day help the U.S. defeat Japan in World War II.” Its strategic position has proven useful time and again for mariners and aviators of all shapes and sizes. Throughout its history, the island has proven an important base of military operations as well as a critical nesting site for millions of Pacific seabirds. Today, the future of Midway and its inhabitants are threatened by pollution and climate change.

01 Helicopters on the flight deck of the aircraft carrier USS Midway CV-41, which has been a museum called the USS Midway Museum since 2004 in San Diego California USA Photo Credit Zack Neher

Helicopters on the flight deck of the decommissioned aircraft carrier the USS Midway, CV-41.  The Midway was commissioned shortly after the end of World War II, and was named in honor of the important naval battle that took place at the atoll.  Today, the Midway is a museum in San Diego, where visitors can explore the enormous ship and see what life might have been like on the floating city.

Despite the distance, Midway Atoll is geologically a part of the Hawaiian Island chain, often referred to as the Hawaiian-Emperor seamount chain. Millions of years ago, Midway Atoll was directly above the geologic hotspot that is currently situated under the Big Island of Hawaii. Continental drift took the entire Pacific Plate to the northwest, and as the millennia wore on, erosion brought Midway closer and closer to sea level. As the volcanic island itself subsided further and further, coral reefs grew larger and larger, in a fight to remain close enough to the surface to undergo photosynthesis. Viewed from space, Midway Atoll consists of two islands, surrounded by a ring of coral reef.

02 A drawn map of the Midway Atoll in the Pacific Ocean with Sand Island Spit Island and Eastern Island Drawn and Photo Credit by Zack Neher

A map of Midway Atoll.  The three small islands are at the bottom of the map, and the entire atoll is defined by the shallow reefs.

There is no archaeological evidence that Polynesian navigators found their way to Midway, although some of their stories do seem to allude to the atoll. Midway first came to the attention of Western society in 1859, when Captain N.C. Brooks claimed the atoll for the United States under the 1856 Guano Islands Act. This act allowed the U.S. to provisionally occupy uninhabited and unclaimed islands for the acquisition of guano (seabird poop), which, at the time, was worth twenty-five percent that of gold. The nitrogen-rich guano was a very valuable fertilizer, and Midway Atoll was full of it.

03 A large number of cormorants perched on an island covered in guano just off shore at Simon's Town or Simonstad near Cape Town in South Africa with Teddy Castro and Michael Collett Photo Credit Zack Neher

A large number of cormorants perched on an island covered in guano, just off shore at Simon’s Town in South Africa.  Interestingly, this town plays host to the South African Navy, although I was there for the penguins.

If you manipulate a globe so that you are looking straight down at the Hawaiian Island, you can see that the Pacific Ocean takes up nearly half of the Earth’s surface. Anything trying to cross this vast expanse of ocean, be they man or beast, will face enormous challenges. Fortunately, the ocean is peppered with small islands, including the Hawaiian chain and Midway Atoll, which provide critical refuge to both wildlife and human travelers.

04 A drawn map of the Pacific Ocean and Oceania with Hawaii Wake Island Midway Atoll Guam Philippines Formosa Japan Alaska Australia New Zealand New Guinea China Russia Borneo Aleutian Islands Vietnam Mongolia Drawn and Photo Credit by Zack Neher

A map of the Pacific Ocean, with several of the islands mentioned in this post labeled.

Even before the outbreak of the Second World War, Midway would serve as a vital stepping stone across the mighty Pacific. Midway was reportedly the final link of a worldwide telegraph system, whose first message was sent by President Teddy Roosevelt on July 4th, 1903. Midway (as well as Wake and Guam) was also used as a stopping point for the Pan American clippers, a luxurious passenger flying boat that would eventually make flights from California to Hong Kong in three days* (a maritime journey of approximately three weeks).

The Japanese surprise attack on Pearl Harbor on December 7th, 1941 was the final straw that galvanized the United States to finally enter World War II. Although the attack itself came as a shock, American leaders had been preparing for the possibility of a war with Japan since 1911. “Plan Orange” was the designation given to the contingency war plan created, just in case America found herself at war with Japan. With the annexation of Hawaii in 1898, and the procurement of both Wake Island and Guam, the U.S. now had a path across the Pacific Ocean, to be able to reach the Philippines (which were under American control at the time), as well as the rest of Asia. The longest transit for the U.S. Pacific Fleet would be from California to Hawaii, a distance greater than 2,000 nautical miles. Following that leg of the voyage, the ships could hop from Hawaii to Midway, to Wake, to Guam, and arrive at last at the Philippines. Each of these legs was somewhere between 1,000 and 1,500 nautical miles.

05 A highway road sign for Kailua, Kaneohe Marine Corps Base Hawaii MCBH, Honolulu, and Pearl Harbor in front of a Toyota dealership on O'ahu in Hawaii Photo Credit Zack Neher

Unfortunately, I didn’t get the chance to visit the Pearl Harbor Memorial while visiting Hawaii.

Although Pearl Harbor was a major American disaster, the American carriers had actually been delivering planes to Midway and Wake when the Japanese struck, saving them from a fiery fate. A blessing for the Americans, and a curse for the Japanese, who wanted the United States out of the fight for the Pacific. The Japanese Admiral Yamamoto Isoroku hoped to lure the American fleet into battle by attacking the Aleutian Peninsula of Alaska, and wee little Midway Atoll in the middle of the Pacific. Fortunately, American cryptanalysts were able to deliver forewarning of the Japanese attack,** and American Admiral Chester Nimitz was able to position his fleet three hundred miles to the north of Midway, before the Japanese could set up their submarines around the atoll.

06 Aloha Tower in Honolulu Hawaii as viewed from the MV World Odyssey Photo Credit Zack Neher

Aloha Tower in Honolulu, which was painted in camouflage during World War II, to make it more difficult to see in the dark.

The Americans were outnumbered, and outgunned. The Japanese had eight aircraft carriers, nearly three times as many as the Americans, who could only muster three. One of these three, the Yorktown, had been hit a month earlier during the Battle of the Coral Sea, and was in need of repairs, which most thought would take at least a few weeks. In a Muskian feat of incredibly optimistic deadlines and unexpected success,*** repair crews at Pearl Harbor had the Yorktown out of drydock in only three days!

01 A McDonnell Douglas F-4 Phantom II from the VF-21 Freelancers on the deck of the aircraft carrier USS Midway, at the USS Midway Museum in San Diego, California, USA Photo Credit Zack Neher

A McDonnell Douglas F-4 Phantom II from the VF-21 Freelancers on the deck of the USS Midway in San Diego.  Although not active during World War II, some of these aircraft were stationed on the USS Midway while the ship was active, as you can see written on the aircraft’s fuselage.

While the Japanese began their airstrikes on the atoll, the American commanders had launched more than 100 planes, which flew directly to the last known location of the Japanese fleet. Upon arrival, the Japanese weren’t there, and only after a bit of searching did they locate them. Two waves of American torpedo-bombers attacked, most of which were shot down, and the Japanese ships went entirely unscathed.

06 The Grumman F4F Wildcat, an American carrier-based fighter aircraft, on display at the USS Midway Museum in San Diego, California, USA Photo Credit Zack Neher

The Grumman F4F Wildcat, a carrier-based American fighter plane, on display at the USS Midway Museum in San Diego.  Pilots flying Wildcats were present during the Battle of Midway.

The torpedo-bombers were lower altitude aircraft, designed to launch torpedoes close to the surface of the water. To combat them, the Japanese fighters were also at low altitude, leaving their ships vulnerable to attack from above. Conveniently, this was when the American dive-bombers came across the Japanese ships, a group of four aircraft carriers. The dive-bomber attack was able to sink three of the carriers, and the fourth was sunk later that afternoon. The Battle of Midway was won, and marked a significant turning point in the Pacific Theatre.

07 A Douglas SBD Dauntless Dive Bomber on display at the National World War II Museum in the US Freedom Pavilion (The Boeing Center) in New Orleans, Louisiana, USA with Seamus Kieran, Mikaila Bloomfield and Emily Barber Photo Credit Zack Neher

A Douglas SBD Dauntless Dive Bomber on display at the National World War II Museum in New Orleans, Louisiana.

Humans are not the only organism that takes advantage of the Midway Atoll as a resting place in the Pacific.      Nineteen species of seabirds arrive every year to nest on the island, nearly two million of them! The atoll is home to one and a half million nesting albatross, making it the largest albatross colony in the entire world.   The nesting albatross population makes up the largest nesting population of the Laysan albatross (Phoebastria immutabilis) and the second largest nesting population of the black-footed albatross (Phoebastria albatrus).**** Several species of tern, booby, noddy, and tropicbird have also been known to nest on Midway. As of 2004, recovery efforts for the Critically Endangered Laysan duck (Anas laysanensis) began, with the introduction of around forty individuals onto Midway. By 2008, their population had increased to approximately three hundred individuals.

08 A wild Laysan Albatross Phoebastria immutabilis soars above the waves of the Pacific Ocean between Hawaii and Japan in the Pacific Ocean as seen from the deck of the MV World Odyssey on Semester at Sea Photo Credit Zack Neher

A wild Laysan albatross (Phoebastria immutabilis) soars above the waves of the Pacific Ocean between Hawaii and Japan.  The largest nesting population of this magnificent bird is at Midway.

Islands, especially small ones, can be plagued by intense selective pressures that can pose devastating consequences on their native populations. Human development, pollution, and hunting are significant problems for many species, as well as the introduced and invasive species and associated diseases that can come with them. Low-lying islands like Midway will also suffer more intensely in the future with heightened storm surges and a higher mean global sea level. In some cases, island life is a literal example of putting all of your eggs in one basket.

16 Introduced mangrove trees on Moku-o-loe Island Coconut Island Marine Laboratory Refuge marine research station in Hawaii Photo Credit Zack Neher

At some point, mangroves were introduced to the Hawaiian Islands by humans.  Interestingly, I was with my Conservation Biology class here on Coconut Island, learning about the efforts to prevent an invasive algae from smothering the native coral.

For the Laysan albatross in particular, another major threat to its health and well-being is plastic debris. Washed into the ocean as trash and litter, plastic debris will become concentrated by the gyres in the North Pacific, resulting in what many have referred to as the Great Pacific Garbage Patch. Every year, a ridiculous amount of trash washes up on the shores of the island, and it has started to have an affect on the local avifauna. Laysan albatross chicks have been found dead, their stomachs completely filled, and blocked up by, plastic trash. The adults seem to confuse plastic debris for prey, or somehow wind up ingesting it while hunting for food, and wind up regurgitating it for their chicks once they return from the hunt to the nest.

17 Unidentified trash debris floating in the Pacific Ocean a few days out from Hawaii between Hawaii and Japan

Unidentified marine debris (trash) floating out in the middle of the Pacific Ocean.  I was pretty surprised by the amount of trash that you would see just randomly floating in the middle of the ocean, although most of the Great Pacific Garbage Patch is composed of small fragments of non-biodegradable plastics.

Despite these abundant threats (or perhaps because of them), albatross are extremely hardy birds, capable of flying at least 10,000 miles in just one trip, although it will rest on the surface of the water like a duck to rest on its journey. The oldest known bird in the world is actually a Laysan albatross, an individual named “Wisdom,” a female that is at least 65 years old, and successfully hatched another chick back in February of 2016. Nevertheless, albatross are very vulnerable when it comes time to return to these isolated specks of land to breed and raise their chicks, and significant conservation efforts are required to ensure that they don’t decline with the continually increasing challenges that these magnificent birds face.

09 A wild black footed albatross Phoebastria nigripes soars above the waves between Mexico and Hawaii in the Pacific Ocean as viewed from the deck of the MV World Odyssey on Semester at Sea Photo Credit Zack Neher 02

A wild black-footed albatross (Phoebastria nigripes) soars above the waves between Mexico and Hawaii, in the Pacific Ocean.

As a tie-in to this blog post, I interviewed my friend Doug Hartshorn, an employee at the Morrison Natural History Museum, about the time he spent on Wake Island with the Air Force in 1972, for the very first episode of my new The Natural World Podcast!  Check out the link below to listen in!

Episode 01: Adventures On Wake Island Featuring Doug Hartshorn

21 Doug Hartshorn the Museum Coordinator at the Morrison Natural History Museum in Morrison, Colorado Photo Credit Zack Neher

Doug Hartshorn at the Morrison Natural History Museum.

*As conventional methods of maritime navigation such as dead-reckoning and celestial navigation were not always reliable enough to rely on, Pan Am developed a means to transmit a signal from the aircraft, which was received by a station on the island, which was then transmitted back to the aircraft, in order to determine the position of said aircraft.

**There was evidence that the Japanese were planning something big about a month before the Battle of Midway. Although the cryptanalyst team was fairly confident that the target was, indeed, Midway, not everyone was fully convinced. So the team laid a trap for the Japanese. They falsified a radio broadcast, stating that there was a shortage of water on Midway due to the failure of a water distillation plant. Less than two days later, the team was able to decrypt a Japanese broadcast that stated that their mysterious target, which they often referred to as “AS,” had had a problem with their water distillation plant. As a side-note, apparently a number of the Americans hard at work decrypting the Japanese broadcasts were musicians from the American battleship California (damaged in the Pearl Harbor attack). The officer in charge of the team “thought their musical skills might make them adept codebreakers” (Ballard, 1999).

***Elon Musk, the famed CEO of Tesla and SpaceX, is notorious for setting incredibly optimistic deadlines for incredibly complex and difficult projects. By the way, I rode in a Tesla for the very first time today. What a morning.

****There seems to be some disagreement over the more ancient etymological ancestry of the name “albatross,” although the more recent Latin influence of the word “albus” (meaning “white”) is clear (also check out the white tern, featured in a picture above: the scientific name of this animal is Gygis alba). Albus Dumbledore, with his “unmistakable silver beard,” was named by J.K. Rowling to reflect this, and the importance that the color white apparently has in alchemy. Some sources indicate that the name “albatross,” while certainly influenced by the word “albus,” also likely has its roots in more ancient words, as well. One possibility that I read on etymonline.com suggests that it can be traced to the Spanish or Portuguese word for pelican, “alcatraz,” which is also the name given to the prison island in San Francisco, which has been home to a large number of roosting pelicans.

20 A brown pelican Pelecanus occidentalis flying above the beaches of Hilton Head Island in South Carolina Photo Credit Zack Neher

A brown pelican (Pelecanus occidentalis) flying above the beaches of Hilton Head Island in South Carolina.  Apparently, brown pelicans no longer nest on Alcatraz Island.

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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.