Monday, September 17, 2007

The New Whale that Wasn't (but sorta was)

Dear Constant Readers,

After one irregular post I think it is time to get back to my blogging roots. Wait a second, have I ever written in a consistent style? Oh well. For those of you that don't know, my life has gotten rather busy and "interesting" of late, severely restricting my output. How other blogs like Laelaps keep on pumping out those sorts of posts is beyond me. Since I can't predict those fleeting pockets of spare time and inexplicable inspirations the future is still irregular for this blog...

As mentioned here, beaked whales are among my favorite animals. I'm not very good at playing favoritism with animal groups although weirdness and obscurity are essential characteristics. As it turns out, few groups of mammals are as weird and obscure as the ziphiids*. For those of you unfamiliar with the beaked whales they can be described as somewhat deep-diving dolphin-shaped whales** reaching small to moderate sizes (4.5-13m/14-40 feet). Male of the genus Mesoplodon typically have only two large teeth in the mandible which appear to be used in intraspecific combat. The teeth are the easiest way to differentiate the species in the field and as such females and juveniles are quite hard to identify in the field. It is remarked upon by Stewart et al 2002 that there are several species which have yet to be identified in the field. Also remarkable is the rate of mesoplodont discovery; new species have been described as recently as 2001 for M. perrini, 1991 for M. peruvianus, and 1995 for M. bahamondi.

*I may have lost your comment my anonymous commenter but your grammar policing did not go unnoticed.

**They're not related though. The bizarre Australodelphis is a true fossil dolphin noteworthy for converging upon ziphiids.


Alright, I lied, there is no Bahamondi's beaked whale, at least not anymore. Instead of being known for a decade it has actually been around for over 130 years under several different names. This is among the older mesoplodonts being the 6th out of 14+ species to be discovered, but is poorly known even for this cryptic group. In fact if I were writing the McCormick Book of Animal Facts and Feats I'd give this species the record for most poorly known mammalian megafauna species. With only three remains, none being post-cranial, this is the most obscure living mammal I'm aware of...but I'm sure a more erudite person reading this can best this. Still, it's amazing that a mammal probably weighing around a ton has never been seen in the flesh.

So, what is known about this species? Van Heleden et al 2003 in a free article describe the complete history of this species, really saving me a lot of trouble. The lawyer Henry Hammersley Travers sent a mandible and teeth from Pitt Island, Chatham Islands, New Zealand to James Hector in 1872. The following year, Hector, the namesake of Hector's beaked whale, described the specimen as belonging to "Dolichodon" layardii, better known as the bizarre strap-toothed whale. Gray disagreed and classified the specimen as the unique species "Dolichodon" traversii. Hector and McCann subsequently stuck it in M. layardii where it stayed for over a century. In 1986 off Robinson Crusoe Island, Chile a damaged portion of a cranium was discovered, found to be distinct from all other species, and was placed in the species M. bahamondi in 1995. Another damaged skull was found in White Island, New Zealand in the 50's and was classified as the obscure Ginkgo-toothed whale until DNA testing demonstrated that it did not belong to any known species. It was subsequently classified as M. bahamondi until the van Helden et al paper demonstrated that all three specimens were from the same species. Thanks to priority the old "synonym" of M. traversii was resurrected and we sorta got a new species of whale.

Despite the surprisingly tangled classification of only three specimens, the morphology of this species is quite distinctive. The teeth found in the original specimen are quite large at 23cm/9" and shaped like a spade (whaling flense). They are shorter and wider than the strap-toothed whales' teeth and do not appear to arch over the rostrum. While there have been sightings of unknown cetaceans in the past, I've heard no reference to a Mesoplodon sp. with abnormally large teeth. In addition to the teeth this species also has a rostrum wider than any other mesoplodont, and the distance of two premaxillary foramina is smaller than any other mesoplodont. The van Helden et al paper was multi-disciplinary and included DNA examination which revealed it to be a fairly distant relative of the strap-toothed whale. A field guide by Stewart et al published while the paper was in press mentioned that it may be closely related to and similar in appearance to Andrews' beaked whale, but the phylogenetic tree in van Helden et al suggested otherwise.

There we have it, a still fairly long post on an animal that is almost entirely unknown. It is amazing that an animal apparently reaching 5-5.5m/16-18 feet (according to a Stewart et al's field guide) could almost totally evade human detection. Behavior and natural history are of course unknown, but it can be assumed whatever surface behavior they have is inconspicuous and not diagnostic, despite the teeth. For those concerned about the degrading state of the oceans it must be frustrating that a creature larger than most great white sharks has slipped by with only three fragmented remains. Even for other ziphiids known from many more remains and even hunted, none of them seem to be particularly well known. This species hasn't been heard from in over 20 years, but that could be due to its (presumed) cryptic behaviors. Either that or we're losing species before we even know anything about them. And I can't help but wonder at what else could be lurking in museums...

I should note that on the topic of Cryptozoology there are two alleged unknown beaked whales known from sightings but I can't come across a more complete description to tell if it is a variation on a known species or not. I believe Bruce Champagne mentioned two more possible types that are apparently yet to be published. Cryptid cetaceans are interesting, but they'll have to wait until I can pick up better resources. Now that my sources are more limited at college (oddly), I'll have to pick my targets wisely. More on internet memes? Nah.

-Cameron



References:

Stewart, Brent S. et al. National Audubon Society Guide to Marine Mammals of the World. Knopf, 2002.

van Heleden et al. 2003. Resurrection of Mesoplodon traversii (Gray, 1874), Senior Synonym of M. bahamondi Reyes, Van Waerebeek, Cardenas and Yanez, 1995 (Cetacea: Ziphiidae). Marine Mammal Science. v. 18, i. 3, 609-621. Available (for free): Here

1 comment:

Caitling said...

Sorry about the last comment, I'm not sure what happened.

You should call you book "The McCormick Book of Animal Facts and Feats, that No One has Ever Heard of and May or May Not Be Real"

You'd be amazed at how clever and invisible some whales are, they always win at hide-and-go-seek, because even when you catch them, you're not sure if you caught them before, or if they're a whale at all.