Before plastic caps filled our shorelines, hermit crabs adapted using tree nuts if no shells were available.
It’s becoming more common to find crabs with beach trash homes. I have friends combing local beaches in search of more crabs for my series. While these are cute images, our trash is becoming a serious problem to the ocean and the animals that call the shoreline home. I often find hermit crabs using a variety of plastic caps from twist top pet bottles, laundry detergent containers, small propane tanks, sports water bottles and beauty supplies.
- Limited number of available shells causing them to make due with the best homes they can find. This is a good example of adaptive behavior.
Hermit crabs are very social animals and often fight over shells. Having a protective lightweight shell that covers the abdomen (soft parts of the animal) is crucial for survival.
Hermit crabs fighting over prime real estate
The battle -
A close-up of the sensitive abdomen (photographed using the MYN technique)
Naked hermit crab
Hermit crabs are scavengers and take advantage of any food washed ashore. They mainly feed on dead fish, barnacles, other crabs, algae, insects, plants, fruit and various seeds. The screw pine (Pandanus odifer) is one of their favorite foods. I imagine long ago these vital plants lined our shorelines in abundance. Numbers are decreasing due to deforestation.
Eventually the fruit drops to the ground and the sweet smell attracts the hermit crabs
Hermit crab feeding
The hermit crabs feed on the the fresh keys and help with seed dispersal. They both benefit in this relationship. The Pandanus tree provides shelter, shade, food for the hermit crabs.
Hermit crab and Pandanus
Eventually the keys dry, turn brown and litter the local beaches. The dispersed keys provide a perfect environment for hermit crabs to blend in with.
Where the treeline meet the beach
Hermit crabs prefer to be in a shell that protects the entire body from predators. Sometimes they have to temporarily adapt with a much smaller shell. The retracted hermit crab tightens up to protect itself. Ball up, play dead and blend into the environment, minimizing the risk of being preyed upon.
Could this be a form of masquerading or just coincidence ? It resembles (mimics) the shape of the screw pine seed to possibly avoid detection from potential predators.
Hermit crab and screw pine seed
Hermit crabs have the ability to ball up tight to protect their eyes. (Transformers)
Hermit crab retracted
Below are some of my favorite images photographed on a portable field studio board (MYN Technique). The crabs are safely placed on a white studio board, photographed and released back into the natural environment (MYN Technique).