Tuesday, August 24, 2010

YPM ICH 23585: A baby porcupinefish!

Last week Twan Leenders, a conservation biologist for the CT Audubon Society and a Peabody curatorial affiliate, deposited a baby porcupinefish for the collection! Here are pics, taken by Twan. The little guy is about the size of a quarter:



Pretty cute, huh? A little boy found it (dead) on the beach of the CT Audubon Coastal Center and brought it to Twan. Twan brought it here, and Greg Watkins-Colwell of our division along with Karsten Hartel of Harvard's Museum of Comparative Zoology identified it.

It's a porcupinefish of the species Chilomycterus schoepfi (common name striped burrfish). Here's what these guys look like as adults (photo from here):


If you think it looks like a pufferfish, you're right. It acts like a pufferfish too-- it can inflate its body to ward off predators, and it's toxic just like a pufferfish. But it turns out it's not actually a pufferfish. It belongs to a very closely related family known as the porcupinefishes (family Diodontidae), as I alluded to earlier in the post.

For more on our new little specimen, the CT Audubon Society has blogged about it in more detail here.


Sunday, August 15, 2010

YPM ICH 8403: Electric elephantfish with big brains

So apparently when you've got a long schnoz, intelligence is something that comes along with the territory. Or so it would seem if elephants and elephantfishes were your only two data points. Elephantfishes comprise the family Mormyridae, and they parallel elephants not only in nasal appearance, but in high intelligence as well, with a brain size to body mass ratio equaled only by our own!

Here are two Mormyrids, species Gnathonemus longibarbis, from YPM ICH 8403, collected in 1956 in Uganda's Lake Kyoga:


Why the long proboscis? Mormyrids live in Africa and tend to inhabit murky lakes and swamps; the proboscis is thought to be a touch organ that helps them locate the mud-dwelling invertebrates that they like to feed on. As far as I can tell though, it's not like an elephant's trunk-- elephantfishes can't suck anything into their proboscis since, as I found on our specimens, as there are no openings at the end. All it does is help find food. In fact, the mouth is actually above the proboscis, not below it! Here is a shot where you can see this:


Why such a big brain? To meet the demands of being electric. That's right, they are electric, and their cerebellum is so specialized and large that it even has its own special name, the "mormyrocerebellum". This mormyrocerebellum is the neural center for coordinating their electricity.

You might be thinking about electric eels right now, which use their electricity to stun prey, but Mormyrids actually use their electricity quite differently, in a dizzying number of ways! Because they live in murky lakes and have poor eyesight, they use it for orientation and navigation. The electric field is continuous and envelops them, so when they swim near an object, the field is interrupted and they are alerted to the object's proximity. They also use their electricity for various means of communication, including territorial interactions, species recognition, individual recognition, courtship, and communicating social status. This is possible because the elephantfish can both output and receive very specific electrical signals--signals that vary by only fractions of a millisecond. Most fish rely on visual and other types of signals for communication, but given their turbid habitat, the Mormyrids' unique electrical system works better for them.


Sources:

Helfman, Gene S., B.B. Collette, D.E. Facey, and B.W. Bowen. 2009. The Diversity of Fishes, 2nd ed. Wiley-Blackwell, Hoboken.

Paxton, John R., and W.N. Eschmeyer. 1994. Encyclopedia of Fishes. Academic Press, San Diego.

Monday, August 9, 2010

YPM ICH 7753: A gruesome fish collected by a Prettyman

A few weeks ago I re-curated this gem:


It's the 3 inch-long head of a Hydrolycus scomberoides, a piscivorous (fish eating) fish of the family Cynodontidae from the Amazon. Common names of this species include "vampire fish" and "sabretooth tetra".

This specimen was collected in 1976 from the Orinoco River in Venezuela by a man distinctively named "L. Prettyman, Jr."! Below is the original label. I can't imagine what it must have been like to grow up with a name like that...

Tuesday, August 3, 2010

Scientists do not step on Hero Shrews

While in general I suppose it's a possibility that a scientist (or anyone for that matter) might step on a hero shrew by accident (or heaven forbid out of malice), the scientists who first discovered the hero shrew's great strength did not have to step on any hero shrews to do so. Nope, it was the savage natives! [yes, cue ironic tone that condemns the attitudes prevalent during colonialism]. Seriously though, all they had to do was talk to the Mangbetu people of the Congo, who were quite knowledgeable about local natural history (and I imagine learned of the Hero Shrew's strength by observation or accident). Taking a cue from a reader, I did some investigating and wanted to clarify this whole matter, lest anyone think that scientists are ruthless hero shrew crushers who systematically stood heavier and heavier men on top of one to test its limits until it squashed.

Evidently, the Mangbetu knew of the hero shrew's strength and brought it to the attention of naturalists Herbert Lang and James Chapin during the American Museum of Natural History Congo Expedition, 1909-1915. Here is Lang's account from his field notes (which can be found in Allen 1917):

"The natives of these regions, especially the Mangbetu, who are well acquainted with the shrew, first called our attention to its abnormally strengthened back-bone by their performances upon captive specimens ... Whenever they have a chance they take great delight in showing to the easily fascinated crowd its extraordinary resistance to weight and pressure. After the usual hubbub of various invocations, a full-grown man weighing some 160 pounds steps barefooted upon the shrew. Steadily trying to balance himself upon one leg, he continues to vociferate several minutes. The poor creature seems certainly to be doomed. But as soon as his tormentor jumps off, the shrew after a few shivering movements tries to escape, none the worse for this made experience and apparently in no need of the wild applause and exhortations of the throng."

So impressed were the Mangbetu with the hero shrew that, in addition to frequently showing it off to visitors, they wore parts of the shrews as talismans, believing them to bestow invincibility. Here are Lang's field notes on the subject:

"These people feel convinced that its charred body or even its heart, when prepared by their medicine-men, transmit truly invincible qualities, if worn as a talisman or taken like a medicine. Perhaps this mystic reputation has often contributed to make of a brave man a real hero, wherefore the Mangbetu gave it a name meaning 'hero shrew.' Those engaging in warfare or setting out upon equally dangerous enterprise such as hunting elephants are anxious to carry along even a fraction of the ashes of this shrew. Though only worn somewhere about their body, they believe that neither spears nor arrows, nor any kind of attack can seriously injure them, much less bear them down. One can easily imagine that by the removal of the inhibitory influence of fear their courage, cunning and cleverness are set free for the best possible acheivements."

Thus both the common name of Scutisorex somereni and our knowledge of its colossal strength come from the Mangbetu people. It turns out that the hero shrew had been described by scientists as a species in 1910--previous to Lang's and Chapin's encounter with the Mangbetu people--but the unique backbone structure had been completely overlooked because it was custom then to only take the skull and skin for scientific study! I wonder how long it would have taken us to learn of the hero shrew's extraordinary backbone had Lang and Chapin not run into the Mangbetu people ...

Here is one more shot of the hero shrew's spine, viewed from above, versus a "normal" shrew of the genus Crocidura. Taken from Allen 1917:



References:

Allen, J.A. 1917. The skeletal characters of Scutisorex (Thomas 1910). Bulletin of the American Museum of Natural History. 37, pp. 769 - 784.