Tasmacetus on Film

I’m late to the story, but the first-ever video of the beaked whale Tasmacetus shepherdi is beyond irresistible.

The 2006 paper referenced in the video is undoubtedly Pitman et al. (2006), which provided the first accurate description of the whale’s coloration. It is mind-boggling that the external appearance of a whale could be uncertain until so recently. Indopacetus, the external appearance of which wasn’t nailed down until 2003, looks very similar to Tasmacetus but clearly isn’t the species in the video. The pale melon, long dark beak and white shoulder patch considered diagnostic for vessel encounters with Tasmacetus (Pitman et al. 2006) are clearly visible and I think I even caught a glimpse of the very distinctive cape. The 4 (or 5?) whales in the video are consistent with other observations of group size for the species (3-6), although the previous sample size was only four (Pitman et al. 2006). One interesting detail from the video is that it answers Pitman et al. (2006)’s query as to whether or not the blow of this species would be visible from a vessel, as it shows that the blows are perhaps as prominent as those from Berardius and Hyperoodon. There are undoubtedly other things that the video shows that I haven’t picked up on, so I’ll try and get the jump on the paper when it eventually surfaces.

_Tasmacetus_ is a bit toothier than your bog standard beaked whale. From Mead and Payne (1975).

The coloration of Tasmacetus is curiously dolphin-like as it exhibits a dark cape, flipper stripe and no differences between sexes and age groups (Pitman et al. 2006). Another curiously dolphin-like trait is that in addition to the battle teeth, both jaws have full sets of functional teeth (Pitman et al. 2006). This is not necessarily a radical departure from other beaked whales. The fossil ziphiids Messapicetus and Ziphirostrum apparently had functional teeth in both jaws (Lambert 2005) despite being relatives of the conventionally toothed Ziphius (Bianucci et al. 2007). Mesoplodon grayi has apparently functional teeth in its upper jaw and non-battle teeth are sometimes present in the lower jaw as well (Robson 1975). It’s certainly puzzling what retentions and/or reversals could have led to such an odd arrangement of toothy species, although since beaked whale systematics show no sign of getting resolved any time soon perhaps it’s best not to think about this at the moment. Ziphiids certainly don’t seem to be close relatives of dolphins so it seems likely the dolphin-y traits of Tasmacetus are convergences rather than retentions. As for why they’re pretending to be giant dolphins, who knows.

I also can't resist bizarre reconstructions. This one is fine up until the flippers and then... yikes. From Mead and Payne (1975).

References:

Bianucci, Giovanni et al. (2007) A high diversity in fossil beaked whales (Mammalia, Odontoceti, Ziphiidae) recovered by trawling from the sea floor off South Africa. Geodiversitas 29(4), 561-618. Available.

Lambert, O.. 2005. Systematics and phylogeny of the fossil beaked whales Ziphirostrum du Bus, 1868 and Choneziphius Duvernoy, 1851 (Mammalia, Cetacea, Odontoceti), from the Neogene of Antwerp (North of Belgium). Geodiversitas 27(3), 443-497. Available.

Mead, J. G. (2008) Shepherd’s Beaked Whale (Tasmacetus shepherdi). IN: Perrin, W. F., Würsig, B., & Thewissen, J. G. M. Encyclopedia of Marine Mammals. Academic Press.

Mead, J. G. & Payne R. S. (1975) A specimen of the Tasman Beaked Whale, Tasmacetus shepherdi, from Argentina. Journal of Mammalogy 56(1), 213-218.

Pitman, R. L. et al. (2006) Shepherd’s Beaked Whale (Tasmacetus shepherdi): Information on appearance and biology based on strandings and at-sea observations. Marine Mammal Science 22(3), 744-755. Available.

Robson, F. D. (1975) On vestigial and normal teeth in the Scamper-Down Beaked Whale, Mesoplodon grayi. Tuatara 21(3), 105-107. Available.

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