Tetrapod Zoology

i-8875eab2cdc2b24547dc6ec5d54cdf7a-Otonycteris-hemprichii-Charlotte-Roemer-wikipedia-Mar-2011.jpg

ResearchBlogging.org

In the previous article we looked at the majority of taxa included within the ‘plecotin’ group. As discussed therein, while there may be a clade of ‘core plecotins’, the traditional concept of the group might be paraphyletic. Some plecotins – Idionycteris in particular – might even be outside the clade that includes plecotins and all other vespertilionines. Here we look at a particularly interesting group of vesper bat species that might, or might not, be part of the ‘core plecotin’ clade: the desert long-eared bats (Otonycteris). What makes desert long-eared bats especially interesting is that, along with being desert-dwelling specialists (as you’d guess by the name), they’re ground-foraging gleaners, described as among the most predatory of Palaearctic bats, and well able to prey regularly on scorpions, solifugids and perhaps even on lizards. They also look really, really scary. [Adjacent photo by Charlotte Roemer, from wikipedia].

Occurring throughout arid north Africa and the Arabian Peninsula, and also in central Asia as far east as Pakistan, desert long-eared bats occur in true desert habitats as well as in semi-deserts and oases. They roost in rocky crevices and sometimes in buildings. Like other plecotins, they have proportionally large ears (up to 40 mm long: that’s about half of their head + body length). In contrast to Plecotus and similar taxa, their ears are not connected at their bases by a band of skin. These are large vesper bats, with a mass of 18-30 g and a wingspan of 35-40 cm. [Photo below - showing a female O. hemprichi captured in Sinai, Egypt - by P. Benda, from Benda et al. (2008)].

i-5bec6aa607208d6b62e61991956b4058-Otonycteris-P-Benda-portrait-Mar-2011.jpg

During recent decades most authors have classified all Otonycteris populations as belonging to a single, highly variable species (O. hemprichi) sometimes known as Hemprich’s long-eared bat*. However, variations in skull shape have led to the suggestion that this might actually represent a species complex, or at least deserve splitting into several subspecies. Benda & Gvoždík (2010) examined both morphology and genetics and found that the desert long-eared bats of Africa and the Middle East could be readily distinguished from the central Asian ones, and they concluded that the two should be regarded as separate species. The central Asian species (O. leucophaea) could, in turn, be split into three subspecies.

* Incorrectly spelt ‘Hempriche’s long-eared bat’ in one or two books. The species name is spelt hemprichi by some authors, and hemprichii by others.

Taking scorpion stings to the face and other such acts of badassery

i-c40406b64eee2b10a252ed718f667d1e-Otonycteris-in-hand-Mar-2011.jpg

The eyes in these bats always look relatively large, and they have an alert, aggressive demeanour (I’m basing all this on photos: I’ve never knowingly* seen a live one!). Combined with a pale coat, semi-translucent wing membranes, large ears and impressive teeth, this look makes these bats superficially resemble the much larger, predatory megadermatids (false vampires and ghost bats). Indeed, their low aspect ratio wings and low wing loading led to suggestions that they’re most likely ground-feeding gleaners – possibly of small vertebrates (Norberg & Fenton 1988) – long before this behaviour was properly documented. Observations made since show that they land briefly (2-5 seconds) on the ground to catch prey before chewing nosily, taking off and eating the prey in flight: beetle larvae have been found as stomach contents in some studies, demonstrating a ground-gleaning habit beyond doubt. Holderied et al. (2010) confirmed that, like megadermatids, Otonycteris uses prey-generated noises when hunting, sometimes detecting scorpions via their walking sounds. These bats do use quiet echolocation as well.

* I did see many bats while in Morocco, but was never able to identify them.

Desert long-eared bat diet seems to mostly consist of such terrestrial arthropods as scorpions, solifugids, beetles, cockroaches and crickets, making them “the strongest predator among Palearctic insectivorous bats” (Arlettaz et al. 1995, p. 875). They drop right on to their scorpion prey and may be repeatedly stung on the body and face while subduing them: amazingly, this seems to have no effect and the bats display no evidence whatsoever of selecting scorpions based on their size or toxicity (Holderied et al. 2010). The conclusion must be that they’re generalist predators of scorpions as a whole. They eat the whole scorpion – sting and all – and more than 70% of their droppings are made up of scorpion remains at some times of the year.

i-f9895e74aaf4d9608c6fbb359063e90b-Arlettaz-et-al-1995-Otonycteris-arthropod-diet-Mar-2011.jpg

Norberg & Fenton (1988) suggested that Otonycteris might include small vertebrates in its diet on the basis of wing loading, wing shape and body size. Arlettaz et al. (1995) speculated that Otonycteris may well be in the habit of preying occasionally on the bow-fingered gecko species Cyrtodactylus russowi [for much more on bow-fingered geckos see Lamellae, scansor pads, setae and adhesion... and the secondary loss of all of these things (gekkotans part IV)].

The idea of a predatory vesper bat that attacks, kills and consumes venomous scorpions as well as solifugids and (perhaps) lizards is undeniably badass even though – granted – these prey animals might be just a few centimetres long (the gecko in question is 11 cm long) [below is an image I found in the Tet Zoo archives: it depicts the age-old battle between desert long-eared bats and scorpions. For a larger version, look at the Tet Zoo facebook page]. Arlettaz et al. (1995) found scorpions, solifugids and grasshoppers to form the bulk of the desert long-eared bat diet [see their diagram of diet broken down taxonomically, above], but Benda et al. (2008) reported scarabaeid beetles to be more important. However, the data in the latter study came from an oasis where human impact might influence the bat’s foraging habits and choice of prey.

i-78f2d0c87fc6ba01cbb728c3dd15a05e-Otonycteris-vs-scorptions-cartoon-Mar-2011.jpg

Roaming all over the cladogram

i-d1180aeb0daadaca142a5ccb05b308dc-vesper-bat-cladogram-Mar-2011-2-with-Otonycteris-360-px.jpg

It has proved difficult to classify desert long-eared bats, and don’t assume that they’ve always been recovered close to (or within) ‘core plecotins’; in fact, several radically different phylogenetic hypotheses have been published. As we saw in the previous article, ‘core plecotins’ have a cute, short-faced look whereas Otonycteris looks rather more like snarling demon from hell. Based on this most empirical and scientific rigorous of evaluations, I think it can certainly be doubted that Otonycteris is a plecotin. Koopman & Jones (1970) regarded Otonycteris as a nycticein, close to evening bats (Nycticeius), little yellow bats or rhogeëssa bats (Rhogeesa) and house bats (Scotophilus), but karyotypic evidence later suggested an affinity with plecotins (e.g., Qumsiyeh & Bickham 1993).

Hoofer & van den Bussche (2001) found Otonycteris to be well removed from a plecotin clade, and to instead be the sister-taxon to an Antrozous (pallid bats) + Rhogeesa clade. In other words, they found Otonycteris to be part of Antrozoini, a clade we haven’t yet discussed in this series (don’t worry, it’s coming soon). This is really interesting given that pallid bats at least are notable for their robust jaws and teeth and Otonycteris-like habit of ground-gleaning and preying on (relatively) large animals.

Since then, a larger analysis has put Otonycteris back with the plecotins (Roehrs et al. 2010): sometimes within ‘core plecotins’ and sometimes within a Plecotini + Lasiurini clade. I think it’s safe to say that the phylogenetic affinities of these fascinating predatory bats have yet to be resolved, though an affinity with plecotins in the broad sense does seem most widely supported.

So… that’s all of the plecotin or plecotin-like bats out of the way. Next: hairy-tailed bats or hoary bats. For previous Tet Zoo articles in the vesper bats series, see…

And for previous Tet Zoo articles on bats, see…

Refs – -

Arlettaz, R., Dandliker, G., Kasybekov, E., Pillet, J.-M., Rybin, S. & Zima, J. 1995. Feeding habits of the long-eared desert bat, Otonycteris hemprichi (Chiroptera: Vespertilionidae). Journal of Mammalogy 76, 873-876.

Benda, P. & Gvoždík, V. 2010. Taxonomy of the genus Otonycteris (Chiroptera: Vespertilionidae: Plecotini) as inferred from morphological and mtDNA data. Acta Chiropterologica 12, 83-102.

Benda, P, Dietz, C., Andreas, M., Hotov‎ý, J., Lučan, R. K., Maltby, A., Meakin, K., Truscott, J. & Vallo, P. 2008. Bats (Mammalia: Chiroptera) of the Eastern Mediterranean and Middle East. Part 6. Bats of Sinai (Egypt) with some taxonomic, ecological and echolocation data on that fauna. Acta Societas Zoologicae Bohemicae 72, 1-103.

Holderied M, Korine C, & Moritz T (2010). Hemprich’s long-eared bat (Otonycteris hemprichii) as a predator of scorpions: whispering echolocation, passive gleaning and prey selection. Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology PMID: 21086132

Hoofer, S. R. & Van Den Bussche, R. A. 2001. Phylogenetic relationships of plecotine bats and allies based on mitochondrial ribosomal sequences. Journal of Mammalogy 82, 131-137.

Koopman, K. F. & Jones, J. K., Jr. 1970. Classification of bats. In Slaughter, B. H. & Walton, D. W. (eds.). About Bats: a Chiropteran Biology Symposium, pp. 22-28. Dallas: Southern Methodist University Press.

Norberg, U. M. & Fenton, M. B. 1988. Carnivorous bats? Biological Journal of the Linnean Society 33, 383-394.

Qumsiyeh, M. B. & Bickham, J. W. 1993. Chromosomes and relationships of long-eared bats of the genera Plecotus and Otonycteris. Journal of Mammalogy 74, 376-382.

Roehrs, Z. P., Lack, J. B. & Van Den Bussche, R. A. 2010. Tribal phylogenetic relationships within Vespertilioninae (Chiroptera: Vespertilionidae) based on mitochondrial and nuclear sequence data. Journal of Mammalogy 91, 1073-1092.

Comments

  1. #1 Marcus Good
    March 28, 2011

    Takes scorpion stings to the face? Honey bad^H^H^H Desert long-eared bat doesn’t care!

  2. #2 David Marjanović
    March 28, 2011

    Impressive. I had no idea.

    Acta Societas Zoologicae Bohemicae

    Societatis.

  3. #3 J-Dog
    March 28, 2011

    Take scorpian stings to the face????!!!

    How??? What makes this work???!!

  4. #4 metridia
    March 28, 2011

    Preying on solifugids is decidedly badass. Those things can bite. You can’t evolve immunity to flesh-shearing jaws.

  5. #5 Mike Fisher
    March 28, 2011

    Darren

    Fascinating. I am proud that I’m mammal kin to this plucky bat.

  6. #6 Robert
    March 28, 2011

    Bats vs Scorpions?

    It sounds like a Ray Harryhausen film in miniature!

    Still, if Mongoose and Merekats have a resistance to the venom of the snakes they often prey on, why shouldn’t the Bats have developed a similar capability?

    Nonetheless, they’re clearly well ‘ard!

  7. #7 heteromeles
    March 28, 2011

    Mmmm. Scorpions. Crunchy!

    I bet in 10-20 years we’ll see Otonycterin in the hospitals as the brand name for an expensive scorpion anti-venin. Someone should call Merck and get them started on it.

  8. #8 Jamie
    March 28, 2011

    I’d snarl too if some git held me in that uncomfortable manner. I’ve worked with these bats in a rehab setting and found them calm but determined. Only one even attempted to bite and that was while having a wound cleaned. They are a wonder of nature – as are all bats.

  9. #9 Knightly
    March 28, 2011

    Awww… they’re cute. :3

  10. #10 Vladimir Dinets
    March 28, 2011

    These things look rather similar to pallid bats – roosting habits, appearance in flight, etc. When I was working at a snake farm in Turkmenistan as a kid, we had a small roost in the wall of one of the buildings, and a night roost under a roof edge nearby. On a few occasions when I saw them eating prey it was large spiders, probably wolf spiders or something like that.

  11. #11 Darren Naish
    March 29, 2011

    They do indeed look superficially similar to pallid bats (Antrozous). So, it’s interesting that – as can you see in the discussion (and on the cladogram) above – some workers have suggested an affinity between the two. This is mostly regarded as convergence, however, and most evidence puts Otonycteris among the plecotins. I saw large, pale bats in the Sahara, but they were social, fast-flying and also very noisy, so I don’t think they were desert long-eared bats. Also had close encounters with several solifugids…

  12. #12 Andreas Johansson
    March 29, 2011

    Preying on solifugids is decidedly badass. Those things can bite. You can’t evolve immunity to flesh-shearing jaws.

    Isn’t that pretty much what armour is?

    That said, bats evolving armour seems a tad unlikely.

  13. #13 Craig York
    March 29, 2011

    Having taken a scorpion sting only once in my life,( and that to the foot ) I’ll just say these are clearly tough little fellows. I just wish there was a local variety that
    might develop a taste for wasps. ( which have stung me in the face. twice. ) @Robert(comment 6) The BLack Scorpion could have only been improved by the addition
    of giant, scorpion-eating bats.

  14. #14 Zach Miller
    March 29, 2011

    Sooooo, do these bats reproduce by getting wet after midnight?

    In all seriousness, I have a generic bat-related question: Compared to pterosaurs and birds, bats seem to have pathetically weak arms and legs. I’m looking at that second picture and thinking, “does that thing even have muscles in its limbs? I can see its bones!” Is it just that particular bat, or have bats evolved some other method of powering their flight than pterosaurs and birds? Is it all in the shoulders–which are conveniently covered in thick fur?

  15. #15 heteromeles
    March 29, 2011

    @14 Zach: Actually, birds have most of their muscles in their chests too. There’s a couple of advantages: locate the most of the mass around a center of mass, but more importantly, it minimizes weight, because the shoulder muscles don’t have to move heavy arm muscles that are out on that arm.

    Another thing is that bat bones aren’t hollow, which imposes a bigger weight penalty on them.

The site is undergoing maintenance presently. Commenting has been disabled. Please check back later!