r - K Selection
What is r & K selection?
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Examples of r & K Selection in the Rocky Shores
Warrener
The Warrener is a mollusca that grazes on algae. The Warrener's reproductive strategy is "r" selection. Their reproduction is sexual posing both male and female organs, however they must mate to fertilise their eggs. They lay eggs that then hatch in to free swimming larvae called Veliger. The advantages is their mass reproduction, their defence mechanism by retreating within their shell and they produce more offspring. The disadvantage is they are attractive food for whilst being a larvae and they are slower in their movement which is ideal for their predators and changes in the ecosystem due to harmful substances released into ocean. |
Sea Lion
Sea Lions can weigh up to 450kg, they are very defensive and aggressive. The Sea Loin reproduction is K selection. The breeding age for female is at 3 years old, the male been six years old. The sea lion has an asynchronous 17.5 month cycle The female will usually only breed at the site. The disadvantage for their continuum of reproduction strategy is the morality rate of the pups due the environmental conditions of the colonies, the attack of the males, disease and malnutrition depending on whether pupping occurred during the winter or summer months. The advantages is that prolonged nursing of the pup which can be between 15-18 months until the next pup is born, and there is a longer life expectancy. |
Grasped Shore Crab
Spider Crabs are found around intertidal zone and have long hooked hairs.
The Grasped Shore Crab reproductive strategy falls within the (r)" Quick and many. After mating the eggs have an incubation period of 1-2 months. There is usually hundreds of thousands eggs and once they have hatched they drift away from their mother. Now as larvae they drift along with the ocean currents and as plankton their survival numbers they are vulnerable to predators that feed upon them however as they easily breed there is not a signifiant fall in their population numbers.
Spider Crabs are found around intertidal zone and have long hooked hairs.
The Grasped Shore Crab reproductive strategy falls within the (r)" Quick and many. After mating the eggs have an incubation period of 1-2 months. There is usually hundreds of thousands eggs and once they have hatched they drift away from their mother. Now as larvae they drift along with the ocean currents and as plankton their survival numbers they are vulnerable to predators that feed upon them however as they easily breed there is not a signifiant fall in their population numbers.