The remarkable noses of dik-diks

I'm fascinated by weird and flamboyant nasal structures, so here's a dik-dik, a recent addition to the Zoological Museum of Naples

The dik-dik displayed at the Zoological Museum of Naples.

Specifically, this is a Damara dik-dik, often treated as a subspecies of the Kirk's dik-dik (as Madoqua kirkii damarensis), and thus labeled as such here, but elevated to full species level by some authors (as Madoqua damarensis) (see for example Castelló er al. 2016).

Dik-diks are quite small antelopes with a series of adaptations to desert environments, the most characteristic of which is their elongated snout: the enlarged nasal cavity, which features a moist, black mucosa, allows increased air flow through the nostrils, cooling the blood directed to the brain via evaporative cooling, while also minimizing water loss. Brain overheating is thus avoided, as the brain is made cooler than the core body temperature (Castelló et al. 2016; Blank & Li 2022). Gunther's dik-diks (Madoqua guentheri) live in the most arid habitats and have the largest nose among dik-diks, while it's moderately elongated in Damara dik-diks (Castelló et al. 2016; Blank & Li 2022). 

As mentioned above, dik-diks noses also seem to have a role in preventing water loss, as they have been observed licking drops of condensed water from exhaled air from their snouts, and may also prevent heat loss and aid in selection of plants with a high water content: many species, including the Damara dik-dik, obtain most of their water from the plants they eat, being virtually independent from surface water, but they may drink from it when given the chance (Castelló et al. 2016; Blank & Li 2022).

The same specimen, from a different angle. Note the crest of hair.

Other adaptations to life in deserts include the ability to lower their metabolic rate for water saving, the production of highly concentrated urine (apparently only desert rodents can achieve higher concentrations among mammals), and apparently their feces have the lowest water content among ungulates (Blank & Li 2022).

Also notice the enlarged preorbital glands, which are used in scent marking, and the crest of hair on the forehead, which can be raised when the animal is alarmed or displaying (Castelló er al. 2016).

You can also tell this is a male, as only males possess horns among dik-diks. Dik-diks are also among those antelopes in which females tend to be larger than males (Castelló er al. 2016).

References 

  • Castelló, J. R., Huffman, B., & Groves, C. (2016). Bovids of the World: Antelopes, Gazelles, Cattle, Goats, Sheep, and Relatives. Princeton University Press. http://www.jstor.org/stable/j.ctt1803z89
  • Blank, D., Li, Y. (2022). Antelope adaptations to counteract overheating and water deficit in arid environments. J. Arid Land 14, 1069–1085. https://doi.org/10.1007/s40333-022-0076-y

Comments

Post a Comment

Popular posts from this blog

Nope, this is NOT Dilophosaurus

Image
The large double-crested theropod dinosaur displayed at the Museo delle Scienze (MUSE).   Surely this is Dilophosaurus right!? Surprise, it's not. Nope, the mounted skeleton you see in the photo, a cast displayed at the Museo delle Scienze (MUSE), is not actually Dilophosaurus wetherilli . What you're actually seeing here is instead another early theropod dinosaur, the Chinese  Sinosaurus triassicus.  Despite the name, Sinosaurus is from the Early Jurassic, and it's an early example of large theropod dinosaur: it's been recently estimated at around 5-6 m long and more than 800 kg in weight (Liang et al. 2024). Other than S. triassicus , a second species, S. sinensis , is usually ascribed to the genus (see Zhang et al. 2023 and references therein).  Another view of the same mounted skeleton, from a slightly different angle. Note the somewhat surprisingly thin skull. As you can see from the photos, Sinosaurus had a relatively delicate skull construction with a pair ...
Read more

Moose, and why they’re so amazing

Image
The moose ( Alces alces ) is quite an incredible beast. Me being absolutely flabbergasted by the sheer size of a European moose displayed at the Turin Museum of Natural History. But just how big can moose get? It’s a survivor of the Last Glacial Maximum, and while the European moose ( A. a. alces ) currently ranges in northern and eastern Europe (Norway, Sweden, Finland, Baltic States, Belarus, Russia and Ukraine) and Poland, with some vagrant individuals in Croatia, Hungary, Romania, and Slovakia and some isolated populations in Austria, Germany and Czech Republic, subfossil remains have also been found as far south as Spain, the UK, Switzerland and Italy. The species has progressively restricted its range up to historical times, mainly due to habitat destruction and overhunting (Niedziałkowska et al. 2024). It’s the largest modern deer (Cervidae), with the probable largest individual being estimated at 816 kg, and with unconfirmed reports of individuals exceeding a ton (Wood 1976, 19...
Read more

Deer are weirder than you think

Image
  One of the incredible suspended taxidermy displays at the Museo delle Scienze (MUSE), showing two male Central European or common red deer ( Cervus elaphus hippelaphus ) entangled in combat. In some rare instances interlocked males can no longer separate, and they usually both die. As promised in the previous post , here's more on deer and why they're so fascinating. For how mundane we may find them, deer (family Cervidae) are actually some of the weirdest mammals you can think of, for a variety of reasons, which include laryngeal modifications to enhance their calls during rut, ancient hybridizations, bipedal walking, carnivoran-like aggressive posturing and roaring, and much more (if you want to know more on this stuff, as you should, Darren Naish has previously blogged on all this here , here and here ). But what deer are most renowned for, and arguably their weirdest specialization, is their headgear: instead of just evolving horns (keratinous structures with a bony core...
Read more