I did not realize that the mail of Judy Philip, which I thought
was a private mail to me, in reality had appeared on the Birding-aus list.
I replied also privately, but maybe i should send this reply also to the
entire list, even though my colleague Alistair Poore (who has visited me in
Tromsø, small world!) already has done an excellent job replying to the
queries.
here is what I wrote to Judy.
Judy,
It is amazing that there is no commonly accepted
vernacular name for amphipods in English, as there is one in many other
languages. The ones on the beaches are beach-hoppers, and the ones in the
rain forest landhoppers, while in Britain the ones in freshwater often
are known as scuds. They are usually from a few mm to a few cm
long--sorry, I grew up metric--, but a few in the deep sea grow to much
larger proportions, 20-30 cm. generally, as many cold-blooded animals,
they are larger in cold water (Antarctic, but also e.g. on Svalbard) than
in the tropics, and they also retain a much greater diversity in cold
water, compared to e.g. shrimps and crabs, this may well be because
amphipods have direct development: the young are kept in a broud pouch
under the belly, the marsupium, and their develop until they hatch as
miniature replicas of the parents. (thus no pelagic larvae)
Groundwater amphipods have been collected from bores, but
I do not think they tolerate especially high water temperatures. They
also occur in surface water, and are e.g. common in the Tasmanian lakes.
As amphipods do not have a carapace (shield), they
fossilize not well, and we have therefore disappointingly few fossils;
the best ones stem from amber, are not particularly ancient, and look
just like modern amphipods. But the group itself is thought to be
ancient; there just are no fossils, which makes our task in studying
their geneology and phylogeny more complicated still.
And yes, birds eat a lot of amphipods. the pelagic
hyperiid amphipods are a well-known important food-source for many
seabirds, and there is abody of literature about this both from the
Arctic, and from the Antarctic, as well as from the Paficic coast of
Canada. Infaunal amphipods of mudflats, especially the often extremely
numerous Corophium species, are a favourite food of shorebirds, and again
, there is a lot of literature on the topic. Also the shorebirds on sandy
beaches, e.g. the Sanderlings, in certain areas eat a lot of amphipods.
In the Falklands in 2003 I saw Sheathbills forage on amphipods washed
ashore, and i have a short paper from NZ on Tuis eating amphipods on the
shore. i suppose also the landhoppers will have bird predators, the likes
of lyrebirds etc.
It is dangerous to ask me about amphipods, as I can go on
and on and on on the subject. i hope this was a suitable portion.
Wim Vader
Meanwhile I have also seen the mail by Allan Gillander, talking
about a crustacean found by him within a primitive chordate. Chances are
that he got another amphipod, the famous Phronima sedentaria, first
discovered by the Dane Forskål as early as 1770 in the Red Sea; this
amphipod fashioned a transparent 'house' out of the skeleton of a salp, as
Alan correctly stated, a very primitive and pelagically living
near-chordate. Phronima occurs as a cosmopolitan in all warm seas. There
are a number of other amphipods living in association with salps, but
Phronima is by far the most common and biggest and also occurs in surface
waters, so this is probably what Allan collected.
To return to the birds, just before the blizzard here started in
earnest, 4 Waxwings flew past my office window, yearbird nr 21!
Wim
Vader, Tromsø Museum
9037
Tromsø, Norway
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