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Re: Ceratonykus braincase described



David Marjanovic <david.marjanovic@gmx.at> wrote:


> I thought "myrmecophagy" was not so much used literally ("ant-eating") as
> for ecological niches that involve eating comparatively tiny insects en
> masse instead of attacking them individually, sort of like how a grazing
> herbivore doesn't eat individual grass blades. This would exclude animals
> for which such insects are not "comparatively tiny" (much smaller than the
> head); they would just be ordinary insectivores with an unusual prey
> spectrum. As far as I know, this latter category includes all birds that eat
> mostly ants and/or termites. Unlike myrmecophages, they lack special
> adaptations for eating insects en masse (long tongue, tubular head, huge
> claws...).


I have seen the term 'myrmecophagous' used both ways - which is why I
didn't refute Ron's post about those birds in which ants make up most
of the diet (up to 90% in one case).  But in any case, I'm not sure
your distinction between myrmecophagy and 'ordinary' insectivory is so
clear-cut.


If you were to limit the term 'myrmecophagous' to those creatures that
eats ants and termites en masse, and have special adaptations to suit,
then it's not always so straightforward deciding what is
'myrmecophagous' and what is 'insectivorous'.  When it comes down to
it, it's hard to define myrmecophagy so strictly, because there are
vertebrates that feed en masse on termites and ants without having all
the special adaptations you mention (long tongue, tubular head, huge
claws); and some vertebrates have some of these adaptations, but are
essentially insectivores that have a preference for termites or ants.


The numbat, which feeds almost exclusively on termites and (to a
lesser extent) ants, has some myrmecophagous adaptations, such as a
long tongue, and a long snout that is somewhat tubular; but the claws
are not very specialized for digging (the foreclaws show only minimal
enlargement).  Like the aardwolf, the numbat can't break open tough
termites mounds (except if the outer layer is especially thin, or
already compromised - such as by rain), and obtains most if its insect
prey by scratching at the soil surface, or turning over dead wood.


The aardwolf has even fewer adaptations for myrmecophagy - and also
tends not to attack mounds, but goes after free-ranging termites.  In
this respect, is its behavior any different to an insectivorous bird
that plucks up ants or termites individually?


The sloth bear imbibes termites in large numbers from mounds, which it
can breach.  It's an omnivore that feeds on termites en masse, but has
relatively few adaptations - does it fit your strict definition of
myrmecophagous?


I take your point: ants and termites are lumped together as the
targets for myrmecophagy, simply because their colonial/eusocial
ecology means they are concentrated in large numbers, and thus offer a
large amount of highly localized biomass as food.  The two insect
groups are not closely related: ants are hymenopterans (likes bees and
wasps), and termites are derived blattarians (cockroaches).  But
unless an animal attacks the termite- or ant-nest, and then eats the
termites or ants en masse, then the animal has to forage for them out
in the open, as it would any other (non-colonial) insect - including
those insects that can also occur in large numbers (aphids, scale
insects, etc).




Cheers

Tim