Squat
lobsters
(Munida quadrispina) on Cloud Sponge
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Cloud Sponge Shrimp
Eualis butleri
Divers often
reported a tiny green sphere in Cloud Sponges. These
turned out to be the green eggs of a shrimp which is
regularly associated with Cloud Sponges in Saanich Inlet. |
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Longhorn
Decorator Crab Chorilia longipes.
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Quillback Rockfish
are commonly present in or around the Cloud Sponges.
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This male Ling
Cod is guarding his mate's eggs.
Only armored fish with scales and squat lobsters, crabs
and shrimp with shells utilize the outer surfaces
of living sponges. Why?
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However,
with the exception of a two or three predators noted in a
separate section, only mobile species of crustaceans and
fish have been found
on living sponges. Many sponges produce chemicals which may
be toxic, distasteful or act as a repellant. Ray Anderson,
a biochemist at Univ. of British Columbia has been unable
to find any such compounds in Cloud Sponges. Could there
be some physical deterrent?
We employed members of three species to examine the surfaces
associated with locomotion after contact with the outer sponge
surface. Each specimen was placed in contact with the sponge for
four to five minutes. |
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Limpet
ventral view with projecting spines
On a limpet
we found on the order of 100 spines projecting from the
foot, the mantle edge and around the mouth |
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Urchin
on sponge
Sea urchins
use a combination of spines and tube feet to move over the
sponge. |
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Tube
foot under low magnification
Many of the
tube feet were pierced by 1-3spines to depth of up to 1mm |
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Tube
foot under high magnification
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Side
view of sponge surface
The spines
are limited to the outer surface and are oriented vertically
with the thorns pointed toward the sponge. The knob like
structures are the spiny ends of 6 rayed pinnules. They
appear to guard the pores entering the sponge. However,
their role in this regard has not been established. |
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I sacrificed a finger
to show that the same holds true for spongologists!!
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Scanning
electron micrograph of spine
The orientation
of the spinelets are reminiscent of those in a porcupine
and presumably serve the same purpose.
However, these spines do not provide absolute protection against soft bodied
animals. We found a brittle star inside a sponge which earlier had been outside.
It must have crawled up the outer surface to get in, where it resided for several
weeks. Also, there are soft bodied predators on these sponges. Discussed.
in the predator section. |
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Spider
crab
Spines were
not seen on the feet of a spider crab and presumably
cannot penetrate the hard outer skeleton. The same would
be true for shrimp and squat lobsters. No spines were
found on any of these animals when they were
placed on the inner surface of a sponge. |
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When all or a portion of a sponge dies all the loose
spicules, including the spines, are washed out and only the
fused main frame remains.
These skeletons become available as substrate for a variety
of organisms.
More information on this subject can be found under HABITAT |
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