Topic 8 Crustacean behaviour Flashcards
What is the name of the habitat where sea meets land?
The intertidal zone
What are organisms that live in the intertidal zone adapted to?
Regular cycles of inundation by water followed by exposure to the air.
How do crabs influence the supply of oxygen and water to the mangrove roots?
Crabs burrow in the mud around the roots and snorkels of the mangrow trees, forming a labyrinth of burrows. At low tide the burrows channel oxygen from the air and fresh rain water direct to the roots. When the tide comes in salt water enters the burrows but is often diluted by the freshwater already present and this lessens the amount of salt that the mangroves take up.
How do crabs influence the supply of nutrients to the mangroves?
Crabs feed on organic material, particularly bacteria, present in particles of soil. They take balls of soil down into the burrows as the tide comes in and effectively recycle the organic matter for the mangroves. Some crabs gather up leaves and store them in burrows, where decay releases nutrients that the mangrove can utilise.
What do male fiddler crabs use their large claw for?
Combat and siaplay.
What do male fiddler crabs use their large claw for?
Combat and siaplay.
Define autotomy
The process of casting off a limb of appendage when an animal is under threat or direct attack
What do fiddler crabs feed on?
Detritus, extracting nutrients from microbes living in it
What would be a consequence of a male losing their large claw in a fight?
The male would lose the visual signal that it was a male and would be pursued as a female
Name three mating tactics seen in fiddler crabs.
- Standard gambit
- Herding
- Dig out
Outline the standard gambit mating tactic.
Most common tactic among fiddler crab species that surface mate. Mates initiate courship by approaching a female at her burrow entrance. Males delicately stroke the side and/or dirsal surface of her carapace with his ambulatory legs and minor chela. The male then attempt to grasp the female and turn her so she faces him. If the female is willing she allows this, elevates her body, and tilts backwards, lowering her abdomen. The male grasps the female with his ambulatories and canters his body backwards, lowering his abdomen, resulting in a copulatory embrace. The male begins to rock his body side to side which ceases just before separation. The pair return to their respective burrows. If the female is unwilling to mate she descends into her borrow before the male can turn her or she refuses to lower her abdomen
Outline the herding mating tactic.
A male intercepts a female while shes foraging and as she attempts to flee to her burrow, the male attempts to alter her path and force her into his own borrow. The male traps the female in the burrow and plugs it with sediment. If successful, she remains with him for 1-3 days before both crabs emerge and part company.
Describe the dig out mating tactic.
Mating occurs on the surface and involves the male digging the female out of her burrow. As the tide comes in, males locate and reopen female burrows and as the female emerges, attempt to mate with her on the surface.
What do the body fluids of marine invertebrates generally have an osmolarity equal to?
Seawater
What are osmoconformers?
Aquatic organisms whose osmotic pressure tracks that of the external environment.
