The Achilles' heel and the Achilles' butt of the spotted hyena
(writing in progress)
Here is something about the spotted hyena (Crocuta crocuta) that is obvious in many video clips, but which I have not seen discussed before.
The spotted hyena tends to crouch (tucking in its hindquarters) whenever it is in a fight, e.g. with the lion or the African hunting dog. It seems to be ultra-nervous about the possibility of being bitten or clawed ‘in the bum’, as it were. Certain mustelids show something similar. However, I have not seen the lion or other felids, or any of the canids, performing the same crouch in such situations.
I suspect that many naturalists who have watched footage of the spotted hyena, or watched the species in the field, know this posture. At first sight, it seems an unsurprising reaction in the circumstances. However, on reflection there may be something noteworthy here.
By the way, one of the reasons why the spotted hyena comes over so cowardly to many observers is this distinctive posture, which makes it look fearful despite its physical power and extreme dentition, and its strength in numbers. The crouching posture in fights is accompanied by a slack-jawed grimace. In general, the spotted hyena seems to be ‘shitting itself’ in fear of being bitten or clawed.
What is strange about this is that the spotted hyena should have such a fearsome mouth, and yet such a fearful rear end. Why is this species so concerned about being bitten or clawed at its posterior end?
The crouch is particularly odd because it seems suddenly to reverse another posture that is extremely characteristic of the spotted hyena, i.e. confidently erect tail with a dark tassel flagging the tail. The animal flips from holding its tail upright to crouching with lowered tail in a split-second, as if to go from a signal of confidence and cockiness to a signal of submission and fear, with extreme abruptness when approached rapidly from behind by an aggressor.
I suspect that this crouch is a reflection of the vulnerability of two features of the groin that are not shared with lion or hunting dog etc.: the peniform clitoris/penis and the udder.
The peniform clitoris and the penis dangle to some extent in the groin when flaccid. In this way the spotted hyena differs from the lion (which has a penis far too small to offer a target to any aggressor’s bite) and canids (in which the penis is slung far forward out of harm’s way). The udder and teats of the female spotted hyena dangle low enough that they may be relatively easy for another carnivore to damage in a fight, by biting or clawing.
Furthermore, the poor acceleration of the spotted hyena (owing to its carpal and tarsal joints being specialised for endurance running) means that it must lack confidence in evading being bitten/clawed by a last-second evasive acceleration. It consequently chooses to collapse its hindlegs, even though this further reduces its mobility and agility. In effect, the whole posterior of the spotted hyena, although adaptive in certain ways, seems like a liability in this kind of close fighting.
The following video clip shows the crouching posture of the spotted hyena in a fight with the African hunting dog: https://www.youtube.com/watch?v=hJujcHvR0_I .
Other worthwhile points in this video include:
- you can see the penis or peniform clitoris dangling visible at times, showing the target which I think the spotted hyena is trying to protect by crouching, and
- the last part of the clip really shows the power of the spotted hyena in ripping apart an impala carcase.
The following video clip shows two individuals of the spotted hyena beset by a group of the African hunting dog https://www.youtube.com/watch?v=F7BMQvV8l2U .
Against so many individuals of the hunting dog, mere crouching is insufficient protection and here the spotted hyena has taken to jamming its rear end into thorn bushes to protect itself. This hugging of spiny shrubs with its rear, at the expense of its mobility, again shows how vulnerable it feels about its posterior.
The crouch seems to have been incorporated also into the INTRASPECIFIC bowing display, used for example by a suitor approaching an oestrus female (please see photo below).
Crocuta crocuta vs Lycaon pictus:
http://i17.photobucket.com/albums/b67/reddhole/WildDogsAttackingHyena001.jpg
Crocuta crocuta:
http://cdn2.arkive.org/media/E7/E7055247-3CBF-40FF-B908-C661BE645027/Presentation.Large/Spotted-hyaena-in-apeasement-bowing-display.jpg
I have shown, above, that the spotted hyena seems to have an ‘Achilles’ butt’. This is in the sense that there is something so vulnerable about its rear end that it needs to crouch when attacked by other carnivores, thus reducing its ability to spin or lunge, and certainly reducing its ability to bite back.
This effect is so strong that the spotted hyena, otherwise a powerful adversary, is reduced to a pathetic object of target practice when attacked as a single individual by a group of e.g. the African hunting dog (Lycaon pictus).
The following video clip https://www.youtube.com/watch?v=lOyhX1ICD48 illustrates this excellently. As long as the various individuals of the hunting dog keep snapping at its rear end (in this case the vulnerable udder in particular), the spotted hyena is reduced to impotent self-defence with no prospect for retaliation. Its front end, although fearsome owing to its teeth and bite, cannot be deployed in this situation.
Although the African hunting dog cannot kill the spotted hyena in this interaction, it sure has fun with it and gives it a hard time with a degree of impunity.
My point is that this is not just a case where the hunting dog gets the upper hand by virtue of sheer numbers, against a lone hyena. There is another level evident here which I think the conventional view has overlooked: that the whole body-design of the spotted hyena exemplifies the principle of the Achilles’ heel.
The spotted hyena is essentially unrivalled as regards the force of its bite, but for some reason its groin is its liability, so much so that it is relatively easy for any more than two individuals of another species of predator (or presumably also within the species of the spotted hyena) to incapacitate the bite by threatening damage to the udder (and probably penis/peniform clitoris).
The udder seems in effect to be a ‘soft underbelly’ of the spotted hyena, presenting a target large enough that the hunting dog or another carnivore can easily bite or claw it, which presumably would risk serious injury because the spotted hyena has placed such reliance on the udder as a central feature of its life history strategy.
But it cannot be just the udder because every individual of the spotted hyena seems to react this way, suggesting that the spotted hyena is also nervous of its genitals being bitten/clawed, i.e. nervous to a degree unmatched in other carnivores.
Another good example of this can be seen here: https://www.youtube.com/watch?v=0GrzK4TCy1s . And another good one here https://www.youtube.com/watch?v=-ngFNzdq7zw .
I see two ‘Achilles’ heels’ in the body design of the spotted hyena.
The first is the literal heel, i.e. the hock or tarsal joint, which is so specialised for endurance running (at a canter) that it is relatively poor for sheer speed (it’s not just acceleration because in that video clip of a mature male individual of the lion catching up to an individual of the spotted hyena, the course was so long that both species were running flat-out for perhaps a hundred m).
The second is the heel of the body as it were, i.e. the groin area, which I suspect is again specialised for a long-distance strategy in the spotted hyena although the logic here remains to be elucidated.
Part of this logic is of course that the udder is essential to bringing home sustenance to the offspring after long forays, but somehow the genitals are also part of this design and just how the peniform clitoris facilitates the long-range, endurance-based strategy of the spotted hyena remains a central puzzle for us to ponder.
(writing in progress)
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