Today for #MegafaunaMay, we have the Japanese spider #crab! While this gangly crustacean’s hard carapace reaches a maximum of about 1 foot in width, its legs continue to grow through adulthood and can span more than 12 feet from claw to claw. Like all crabs, it has eight walking limbs and two clawed limbs. The spider crab’s elongated legs help it to scuttle around on the ocean floor off the coast of Japan, scavenging for their food.

Unfortunately, these long legs are quite fragile, and the crabs are often found with missing legs. In fact, spider crabs have been observed walking with as few as five of their walking limbs intact. Fishing nets often rip the legs off as they pass. Luckily, crabs molt periodically, and can regrow their legs during this process.

Most of the time, this #megafauna is difficult prey. Its size and claws help protect it. Immediately after molting, it is slightly more vulnerable to predators such as octopi, which can take advantage of its still-soft new shell. Young, small individuals can also be at risk, but will decorate their shells with kelp and sea sponges as a form of camouflage.

Most of the time, adult spider crabs inhabit depths between 500 and 1000 feet, though they have been found as deep as 2000 feet. They move to shallower waters in order to spawn. The warmer temperature closer to the surface is ideal for helping young crabs grow. Female spider crabs will incubate eggs until they hatch, and then retreat back into the depths. Young spider crabs are usually found in the shallows, and move deeper as they age.

For this third day of #MegafaunaMay, we are looking at the #hippopotamus. This #megafauna can weigh up to 10,000 pounds and reach over 16 feet in length. Although its social systems revolve around access to water, it is also adapted to land, able to run hundreds of yards at speeds approaching 20 mph. These massive herbivores also rely on water to cool themselves, as their skin secretes red sunscreen instead of sweat.

#Hippos are very social, and spend their days resting in pools of water with their herds. They communicate with a wide variety of sounds, including a warning honk which can reach 115 decibels–about as loud as a siren–and produces sound in both air and water at the same time. At night, hippopotamus herds leave their pools to graze on grasses, consuming over 1% of their body weight and returning to their pools by dawn. Male hippos are protective of their herds, resting on the outside edges of pools while females control the center. Males will fight for dominance and use their large, flat tails to spread dung around, marking their territories.

Although hippos rarely eat meat, they possess formidable incisors which are used for defense and fighting. Hippopotami can open their jaws to a whopping 150 degrees wide, and can snap them shut with over 8000 newtons newtons of bite force, making them one of the most dangerous animals to humans–though most hippo attacks occur when humans get too close to young or pregnant members of a herd.

On this second day of #MegafaunaMay, our daily #megafauna is quetzelcoatlus. Named after the feathered serpent god of the Aztec religion, this gigantic #pterosaur lived during the late Cretaceous period in modern-day North America.

With a maximum weight over 500lbs and a wingspan over 30 feet wide, #quetzelcoatlus has inspired controversy over its flight capabilities. For some, its massive size sheds doubt on the idea that it ever flew, but aerodynamic models suggest that it was, in fact, the largest flying animal known to have existed. The towering pterosaur was originally thought to have flown like modern condors by soaring on thermal updrafts in the air. However, more recent research suggests that it instead has more in common with the kori bustard, using its strong wing muscles to complete short, low flights.

Even short flights are impressive from such a heavy animal, and the wings had to be very wide in order to allow them. In fact, quetzelcoatlus’s wingspan is so long that its folded wings touched the ground when it stood on its 6-foot tall legs. This gave the pterosaur a unique approach to walking: each wing had to be moved out of the way of its corresponding foot with each step it too.

Like other #pterosaurs, this species had hollow bones, so its fragile remains are rarer finds than those of contemporary dinosaurs such as the T-Rex. Skulls have given us many hints about quetzelcoatlus’s lifestyle: its large eye sockets suggest that had excellent eyesight; its beak suggests a diet of creatures skimmed out of the lakes near where its fossils have been found; and a bony crest on top of its head could potentially have been used for attracting mates or controlling flight. Although we do not have a complete skeleton of quetzelcoatlus, reconstructions and comparisons to modern species have allowed us to fill in the gaps.

Happy #MegafaunaMay Day! Today’s #megafauna is the #horse. These herbivorous stock animals can stand over 6 feet tall at their shoulders and weigh up to 2700 pounds. They can also run, on average, 30 miles per hour. Coordinating four legs bearing thousands of pounds is no easy task, and horses have six different gaits to make it work at different speeds.

Humans have used horses for transportation, labor, and food for thousands of years–and humans actually played a large role in making the modern-day horse what it is.

55 million years ago, a small creature emerged in North American forests. This was the very first horse species, which browsed for fruits and leaves rather than grazing on grasses. It took a changing climate to bring horses up to size–as forests turned to grasslands, some species developed the grazing behaviors of the modern descendants, and evolved larger bodies and stronger bones to support running. Around the same time, these large horses began migrating into Europe, Africa, and Asia.

By 10,000 years ago, multiple species had spread across these continents while all North American species were extinct. Humans began to use horses for various purposes, and one particular species began to be selectively bred for strength and docility. Starting 4,000 years ago, this species spread explosively across Europe and Asia, and by 3,000 years ago it had replaced all others. This was the modern day horse, which was reintroduced to North America in the 16th century–back in its original home, though not quite in its original form.

If you are also in education, you may be familiar with the soul-crushing period of time that sits between winter and spring break. It’s rather like the early Triassic period: you’ve gone through all the work of establishing what life is going to look like, and then a major event undoes all that. You end up having to rebuild, but you’re not quite at the point where you can start doing fun stuff (like dinosaurs!).

Now that warmer weather is approaching, I feel like I have enough room on my plate for the admittedly rather large topic of this account. So, to help me get back in the habit of researching 1 big friend per day, I am committing to #MegafaunaMay, and will try my best to live up to my name until at least June!

In the meantime, please enjoy this sea scorpion, whose facial expression somewhat matches my students' when I tell them they have to turn in assignments to receive credit. Image from wikimedia.