Friday mystery object #456 answer

Last week I gave you this rugged skull, from a rugged place, to have a go at identifying:

As everyone spotted, this is a whale of some sort (what else has a skull that weird-looking?), but the question is, which species?

The location led to a few suggestions of Arctic / sub-Arctic species like Narwhal or Beluga, but they have a much flatter top section of the skull. In fact, those huge vertical lobes of the maxillae seen here is pretty unusual and quite distinctive (even if it is a ittle weathered and broken):

This reminded me of a specimen in the collections of the Dead Zoo and which I had to check, just to be sure of my identification:

As spotted immediately by Chris and not too long afterwards by Adam Yates and Wouter van Gestel, this is the skull of a Northern Bottlenose Whale Hyperoodon ampullatus (Forster, 1770).

This sub-Arctic species has a distribution across much of the North Atlantic. They tend to stick to quite deep water, which makes sense in the case of the specimen I shared from Iceland, since the Reynisfjara beach is infamously dangerous because it shelves off very steeply into very deep water, making the waves that break along the beach behave in an unusual (and frankly terrifying) way.

Occasionally this species will come into shallower waters, in one (somewhat tragic) case a female Bottlenose Whale swam up the Thames (and is now in NHM, London). Our specimen came from an animal stranded on the Irish coast and there are theories that maritime sound pollution is connected to them being driven into shallower waters.

Well done to everyone who worked out which species this skull is from – hope you’re ready for another mystery next week!

Friday mystery object #409 answer

Last week I gave you this toothy specimen from the Dead Zoo to have a go at identifying:

Everyone spotted that this is the skull of a toothed whale (or large dolphin), but after that, things got a little bit more confusing. In particular, the arrangement of the four pairs of teeth in only the front section of the lower jaw, seems to have thrown a lot people off.

There were several suggestions of Beluga whale, but they have around 40 teeth between the upper and lower jaws and clearly this doesn’t (and even if teeth had fallen out, you’d expect to see some empty sockets in the mandible). There were also suggestions of Narwhal, but they have a maximum of 4 teeth only in the upper jaw and one – or very occasionally two – form the Narwhal’s unmistakeable tusk(s). This is neither a Beluga whale nor a Narwhal.

However, the similarity of this skull to these two species did lead to speculation about whether this might be a hybrid between Beluga and Narwhal – one of the infamous Narlugas (or more accurately Belwhals). Ed Yong wrote about these real, but very rare, animals in the Atlantic a couple of years ago and I recommend having a read. If you do, you’ll discover that only one specimen is known and this is most definitely not it. As disappointing as this will no doubt be for some, we live in a world where hopes and dreams are routinely dashed against the rocks of reality, so let’s get ready to rock.

There are around 30 species of Oceanic dolphin, ranging in size from 50kg to 10,000kg. You can see that this one is a bit bigger than the specimen next to it and it has much broader and more chunky ‘cheeks’ (for want of a better term). This is something I normaly associate with the bigger dolphins that are usually referred to as whales – things like Pilot whales, Killer whales and the species in the Monodontidae that I mentioned earlier.

Most of the Delphinoidea have a lot of teeth to assist with prey capture, but this mystery object has got creative with just 4 pairs in the lower jaw (although obviously not as creative as the Narwhal). This limits the possibilities significantly, since it’s a fairly unusual condition. The other type of whales that only have a small number of teeth in just the lower jaw are the beaked whales, which primarily feed on soft-bodied cephalopods and have repurposed their teeth for competition. The mystery species has, perhaps unsurprisingly, done the very same. So, we’re left with the question of which of the bigger dolphins feeds on cephalopods and has an unusual arrangement of teeth?

The answer, as Adam Yates was the first to share, is the Grampus or Risso’s Dolphin Grampus griseus (G. Cuvier, 1812). They have between 7 and 2 pairs of teeth in their lower jaw and none in the upper. The live animals are quite heavily scarred from their interactions with those teeth.

Stay tuned for another mystery object next week!

Friday mystery object #389 answer

Last week I have this mystery object from the Dead Zoo:

I made it a bit harder than necessary by not including a scale, but then that’s part of the fun – and I think a scale might have made it all a bit too easy.

There were a lot of suggestions about what it might be, mostly referencing some kind of seat / saddle or a patella. It’s probably just about big enough to sit on, although I’m not sure it would be comfortable.

But quite a few of you did figure out what bone it is and more or less what kind of animal. It’s the manubrium (part of the sternum) of a young Humpback Whale Megaptera novaeangliae Borowski, 1781.

Here’s the specimen with our Conservator Silvia for scale next to the manubrium (it’s a little hidden by the bar supporting the mandible here). Silvia’s been busy cleaning the whale, ready for it to be dismantled in the next few weeks.

All the activity around this whale work has been keeping me busy, so I apologise for tardy replies to questions and slightly sparse answers. If you want to see what we’ve been up to, check out the #DeadZooDiary!

Friday mystery object #383 answer

Last week I gave you this slightly mean mystery object from the Dead Zoo to have a go at identifying:

I say it’s mean because it’s just a small fragment from the tip of the lower jaw. It does have some pretty distinctive teeth in it, so it’s probably not the most difficult mystery object I’ve shared, but it’s also from a species in a group of animals that are quite poorly known.

That said, Chris Jarvis was the first to comment and got it right immediately. However, there was a lot of subsequent discussion about how to be sure, given the poor representation of comparative specimens available and the similarities between this species and others in the family. That family is the Ziphiidae, which are the the Beaked Whales.

These cetaceans are rarely seen due to their deep water habits, sometimes diving to depths of nearly 3km (although more usually around 1km) to feed mainly on deepwater squid that they detect using echolocation. Most of what’s known about them comes from strandings – which is where this mystery specimen comes from.

The males tend to be smaller than the females, but the males of most of the 21 Beaked Whale species have tusk-like teeth that they probably use to fight over females, although the behaviour hasn’t been recorded, only deduced from scars and the behaviour of other animals with similar sexually dimorphic characters (there’s an interesting paper on the evolution of the tusks by Dalebout et al. 2008 is you’re interested [pdf]).

The teeth occur in different parts of the jaw and have a different shape depending on the species, so the fact these are located at the tip of the lower jaw means quite a lot of the species can be discounted. If you want to be able to do the narrowing down easily I recommend an old and somewhat unwieldy to navigate, but still very useful online resource – the Marine Species Identification Portal. If you can work out the navigation you can find small line drawings of the skulls of all species in lateral view.

Once you get that far it becomes easier to search for more detailed images of the couple of species it might be, which can yield some great 3D scans to help you work it out. Both Chris Jervis and katedmonson found examples and shared the links in the comments. Here’s a nice one from the NHM, London:

This species (the Cuvier’s Beaked Whale) clearly has bigger tusks than the mystery specimen, which you can see as a scan on the excellent Phenome10K resource*. The mystery object is the distal portion of the mandible of a male True’s Beaked Whale Mesoplodon mirus True, 1913. So well done to Chris Jervis for being the first to get in with the correct identification.

It may seem a bit odd to have just this small portion in the Museum, but as far as records go they represented a managable identifiable voucher for the stranding of the species in Killadoon, Co. Mayo, Ireland back in February 1983. These days we ask for even less material to keep track of strandings – just a small skin sample will do as long as it’s collected and recorded following the guidance of the Irish Whale and Dolphin Group’s (IWDG) Strandings Network.

These samples are stored in alcohol and form the Irish Cetacean Genetic Tissue Bank which is managed in partnership between IWDG and the Dead Zoo to provide genetic data for research into whales. It’s a fantastic resource, but I doubt that anyone could identify the species represented in the samples without access to a genetics lab. And that’s why I like bones best.

*A. Goswami. 2015. Phenome10K: a free online repository for 3-D scans of biological and palaeontological specimens. http://www.phenome10k.org.

Friday mystery object #369 answer

Last week I gave you this weird, but rather nice object to have a go at identifying:

mystery369

Most people seemed to recognise it as the tympanic region (that’s the bony ear-related region) of a whale. But of course, I’m demanding when it comes to getting an identification and there are plenty of species of whale to rule out.

The size immediately narrowed down the possibilities – this is pretty small for a whale. But what really gives it away for the small number of people intimate with the cranial anatomy of whales (which goes beyond even my bone-nerdery), is the spongy bone attached to the tympanic bulla (that’s the bulb-shaped bit of bone that houses the inner ear).

This feature is proposed as a possible pressure receptor that’s found in the Pygmy Sperm Whale Kogia breviceps Blainville, 1838. Amazingly, Conor Ryan identified this on Twitter – his handle of @whale_nerd explains everything you need to know.

Kogia breviceps by George Brown Goode, 1887

These toothed whales only grow to around 3.5m, which is pretty small for a whale. They share some features with their much larger Sperm Whale cousins, particularly in relation to adaptations for echolocation.

I was fortunate enough to meet Conor Ryan at the weekend at the Irish Whale and Dolphin Group conference. There were plenty of whale enthusiasts around and it was fantastic to get a chance to learn more about this incredible group of animals from a lovely bunch of passionate people.

While I was there, I also picked up some useful tips on differentiating between species of dolphin, so I may have to share those with you soon…