Biomedical Ephemera, or: A Frog for Your Boils

Boomslang - Bucephalus viridis [now Dispholidus typus]

Where the elapids and viperids have fangs at the front of their mouth for easy envenomation, boomslangs (a member of the Colubrids) are equipped with regular teeth at the front of their mouth, and venom-injecting fangs at the back. Because of this, even though their venom is extremely hemotoxic, they rarely are able to inject enough into a larger animal (such as a human) to cause death.

However, the bite of a boomslang is not to be underestimated - as it's not always clear when the fangs have punctured the skin due to the other teeth leaving puncture wounds, medical help should always be sought out. The venom is almost completely hemotoxic, and the lack of neurotoxic symptoms can lead bite victims to believe that there was either no envenomation, or that they can just wait for their body to process the toxin.

This mindset is what led to the 1957 death of esteemed herpetologist Karl Schmidt. He believed that the amount of venom he received was negligible, but 28 hours later his blood was so thin that it was coming out of every hole in the body, including his eyes and ears, and no amount of medical treatment could have saved him. Early antivenin administration is critical.

Luckily, even if you're in its natural habitat (forested areas in sub-Saharan Africa), you will probably never encounter a boomslang in the wild. They're timid, generally dwell in trees more than 20 feet above the forest floor, and would much rather eat a small bird than waste their venom on a human. Most bites occur when someone tries to handle or kill one.

Illustrations of the Zoology of South Africa: No. XXII. Andrew Smith, March 1845.

Ways to Die: Snake Venom

The vast majority of snakes that one encounters in the wild (unless you live in Australia or India) are either non-venomous to humans or want nothing to do with you.

However, should you stumble upon a rattlesnake nest or coral snake hole while texting in the middle of nowhere, there will probably be a combination of different enzymes and polypeptides pumped into your body, via the modified parotid salivary glands (right below the ear in humans) that snakes have evolved over the ages, to disable their prey. Of course, you're not prey, but you stepped on a snake while texting. It has every reason to envenomate you.

While all snakes have multiple active enzymes in their venom, all snakes dangerous to humans have either neurotoxins or cytotoxins as a significant component in their venom. For the most part, elapids (such as the cobras and mambas) create neurotoxins, while the viperids (such as vipers, adders, and rattlesnakes) create cytotoxins.

Neurotoxins

Cytotoxins

Images: Top: Bungaris fasciatus - Banded Krait. An elapid, and the largest of the kraits. Has neurotoxic venom. [source] Center Right: Hydrophis robusta [now Hydrophis spiralis] - Yellow Sea-Snake. The longest sea snake, at 3 m (9.8 ft). A member of the Hydrophiinae, separate from other elapids. Though they have some of the most toxic venom in the world, bites are extremely uncommon and often unnoticed. [source] Center Left: Vipera russellii - Russell's Viper. A particularly aggressive viperid. Necrosis and amputation following envenomation not uncommon, due to hemolysis and local cell damage. [source] Bottom: Vipera caudisona [now Crotalus horridus] - Timber Rattlesnake. A venomous viperid endemic to the United States. Primarily hemotoxic venom, very low fatality rate, but very painful bites. [source]

Front View of Muntjac Skull

The muntjac is native to South Asia, but has been introduced to some parts of England, and is considered an invasive species there. The general build of this small deer is similar throughout the genus, with a short stature, short and single-pointed antlers, and tusks.

Muntjacs are also considered the oldest genus of deer extant, having originated at least 30 million years ago (as compared to white-tailed and mule deer, whose direct ancestor evolved less than 5 million years ago). Despite this, and their genetic similarities on an mtDNA level, the various species of the genus are very interesting to geneticists on account of their chromosomal differences. The Indian Muntjac has a diploid number of only 7 in the males, and 6 in the females, while the Reeve's Muntjac has a diploid number of 46. That's a huge difference in one genus, and we're still trying to make sense of how the species can be so similar, yet so incredibly different!

The Naturalist's Library: Vol XXI - Mammalia: Deer, Antelopes and Camels. Sir William Jardine, 1878.

Both the illustration and this skull are from the British Museum of Natural History.

Rhamphotheca says that fangy deer are the best damn thing out there, so perhaps I should make an effort to get over my disgruntled attitude towards them, just because I got bit once.

Catalogue of the Ungulate Mammals in the British Museum of Natural History, Vol IV: Artiodactyla. Richard Lydekker, 1913.

I don't care how tiny they are, deer with fangs will always rub me the wrong way.

Cheek-Pouches of the Macaque Monkey

The macaques, mandrills, mangabeys, and baboons, all have cheek pouches for food storage. They use the pouches while foraging in the same way that hamsters do.

The Anatomy of the Human Peritoneum and Abdominal Cavity, Considered from the Standpoint of Development and Comparative Anatomy. George S. Huntington, 1903.

Musculature of the venom apparatus.

Most venomous snakes can change the muscle tension around their venom sacs when they strike. This regulates how much (and if) venom is injected into the victim. In some species, almost 60% of bites are "dry" - not injecting any venom.

Snake Venoms: An Investigation of Venomous Snakes, with Special Reference to the Phenomena of Their Venoms. By Hideyo Noguchi M. D., 1909.

Skull bones, teeth, and fangs of two venomous snake species.

Erpétologie générale, ou, Histoire naturelle complète des reptiles. A. Duméril, 1834.

I hope it's not just me that thinks that pouched-mouse looks vicious D:

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From A Handbook to the Masupialia and Monotremata by Richard Lydekker. 1896.

Part of the Lloyd's Natural History series.