Savory - Arachnida 1977

284 IV. DE ARACHNOLOGIA
PEAKALL
s
~
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.~
s
ANDERSON
...
... '::: ·;::
2 ~
s
-o ... :§ -o ...
0
~§ 0. .s '-
.S ;.g
c; 8 ~- :s .;: ~ .:::
..-: < a 0. '-' 0.
Alanine 25·:3 27·::1 32·7 25·4 29·3 10·7 6·2 17-6 24·5 9·9
Glycinte 15·3 20·3 2+3 J I·CJ 24·7 13·2 14·5 37·2 8·63 7·8
Serine 11·7 5·3 6·8 11·7 5·3 16·45 6·8 7-4 27-6 14·8
Argcninc 3·8 3·4 3·2 5·0 4·8 4·0 3·4 0·6 1·5 3·6
Aspartic acid 2·1 Hl 1·3 2·3 J.8 8·0 9·2 1·0 6·1 10·5
Isoleucine 4·8 5·7 1·7 5·0 2·1 4·3 +7 0·6 I· 7 3·7
Leucine 3·2 2·9 2·1 3·5 2·2 8·2 5·5 1·3 5·7 5·4
Lycine 2·2 3·2 1·8 1·3 2·1 2-6 7·5 0·5 1·8 9·0
Proline I 0·2 12·8 3·1 3·8 4·7 3-6 10·5 15 7 0·6 7·8
Tyrosine 3·7 1·7 1·8 3·7 Ni 1·6 2·2 3·9 0·9 2·2
Valine 4·8 8·5 1·9 2·7 2·9 6·9 5·8 1·1 6·0 5·4
The silk of pseudoscorpions was analysed Hunt ( 1970), working
with the species }/eobisium maritimum. His figures make an interesting
companson with those given for spider-silk by Lucas and Rudall
(1968):
Hunt Lucas and Rudall
Serine
164 143 (parts per I ,000)
Glutamic acid
Alanine
Aspartic acid
103
176
16
53
100
248
250
27
Pseudoscorpions, like some other Arachnida, also construct or secrete
spermatophores, and Hunt and Legg 1971) analysed these, using no
fewer than 1,500 examples from the Chtlwniw ischnocheles. They
detected 17 amino acids, chiefly:
Glycine 240 (parts per 1 ,000)
Alanine 145
Glutamic acid 123
Serine 89
Aspartic acid 75
VENOM
The composltwn of the poisons injected by the formidable
Arachnida has been investigated by a number of chemists during recent
years, not always \vith consistent results. The subject has been fully
summarized by J unque and Vachon ( 1968).
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33. CHEMICAL ARACHNOLOGY 285
There is an overall
that some half-dm;en compounds are
generally to be found. They are:
Spermine, NH,\CH 2 ) 3 XH(CH,),NH(CH 3
) 3
NH,
Trimethyldiamine, ::\"H,(CH 3
) 3
NH 2
The above are present in the venom of most spiders examined. Aiso in
the list are:
Histamine
Suotaminc or 5-hydroxytryptamine
y-.-\minobutyric acid C,H 8 (1'\H,)COOH
Para-hydroxyphenylamine c.H,(OH)NH 2
Mixed with these a protein and an enzyme that decomposes carbohydrates
are to be included. It appears that the spermine is the most
dangerous constituent of spider poison, while the serotamine is the
chief source of danger in the sting of a scorpion.
The various components of arachnoid Yenom seem to be divisible
as to their different effects. One at least has rapid subduing effects on a
bitten insect, others act more slowly. \Vhen a human suffers seriously,
the troubk is due to a component that stimulates the secretion of
acetylcholine from the nerve endings, quickly exhausting the supply.
Acetylcholine is a neurohormone which causes unstriped muscle to
relax. It is destroyed by the enzyme cholin esterase, so that in its
absence nervous impulses cannot cross a synapsc or reach the muscles
they normally serve.
The venom of false scorpions, which is undoubtedly very virulent
in its action on the normal prey of these small animals, seems not to
have attracted the attention of the biochemists.
PHEROMONES
Pheromones probably play a much part in the lives of Arachnida
(and other invertebrates) than is readily detected, but recent
had attention towards this aspect of animal behaviour, and a
number of interesting results have recorded.
As long ago as 1969, Hegdekar and Dondale showed that sexual
behaviour ii1 the wolf spider Schi;:ocosa crassipalpes was determined by
contact with a sex pheromone. It appears that the compound is secreted
by the female, and the suggestion has been made that its origin is in the
pyriform glands. Thus the drag-lines of the female are effective when a
mature male treads on them, as it seems likely that the chemoreceptive
organs are in or near the tarsi. It is postulated that sex pheromones
help the sexes to meet, and are especially valuable for species that are