title for amphipod section of A SNAIL'S ODYSSEY
   
  Locomotion & tidal rhythms, burrowing, & celestial navigation
 

Burrows provide protection from insolation, drying, and beach-surface predators.  They also enable an animal to be secluded in a moist area during moulting and, for harem-keeping species, provide a safe area to keep the females.

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  Burrowing
 

Studies on burrowing are considered here, while studies on LOCOMOTION & TIDAL RHYTHMS and CELESTIAL NAVIGATION are dealt with elsewhere.

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Research study 1
 

drawing of a gammarid amphipod showing external features courtesy Eugene Kozloff, University of Washingtonphotograph showing territorial spacing among burrows of sandhoppers Megalorchestia californiana courtesy Dave Cowles, Walla Walla University, Washington


















Amphipods burrow using their 1st gnathopods and first 2 pairs of walking legs to scratch loose the sand and pass it to the uropods (see drawing of appendages).  The body is extended to push the sand away.  Megalorchestia californiana kicks sand in opposite directions, creating 2 piles of sand leading from the mouth of the burrow (see photograph upper Right).  There appears to be no substance added to the burrow wall to help maintain its cohesion.  Adjacent burrowers tend to maintain a separation distance of 20-60cm depending upon population density.  Adult burrows may extend 30-40cm into the sand, while juvenile burrows are generally less than 10cm deep.  The burrows appear to be abandoned each night and new ones created.

photograph of male talitrid amphipods Megalorchestia californiana fighting over possession of a burrow, courtesy Ingrid TaylarMale beachhoppers Megalorchestia californiana often fight over burrow access, especially in early daylight hours.  The fighting involves head-butting and shoving with antennae, and can be sufficient to dislodge a “lesser”, usually smaller male from a burrow opening.  Fighting is probably less energy-demanding than digging a new burrow and, if the burrow contains a reproductive female or, better still, a harem of females, then the effort is doubly rewarded.  Bowers 1964 Ecology 45: 677. Photograph of burrows courtesy Dave Cowles, Walla Walla University, Washington wallawalla.edu

 

 

Two male Megalorchestia californiana dispute
ownership of a burrow 3X. Photograph courtesy
Ingrid Taylar, Seattle, Washington & FREE QUARK

 

Number1 in a sequence of 3 photos showing burrowing in a talitrid amphipod Megalorchestia californiana
A male Megalorchestia californiana in pre-burrowing posture 3X

Number1 in a sequence of 3 photos showing burrowing in a talitrid amphipod Megalorchestia californiana
Sand is passed from the 1st pair of gnathopods and first 2 pairs of walking legs posteriorad to the uropods
Number3 in a sequence of 3 photos showing burrowing in a talitrid amphipod Megalorchestia californiana
The sand is pushed to either side of the rear of the body by the uropods
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