This Crab is not crabby
This land crab has visited us for 3 years consecutively. It comes to taste some mangos we put out. This year it was filled with eggs - can you see them? It comes down into the beach to mate and then lives on land.
How do Crabs Find Mates? Wave, Sing, Vibrate & Secrete!
Crabs are decapod crustaceans of the infraorder Brachyura, which first appeared during the Jurassic Period. Crabs attract a mate through chemical (pheromones), visual, acoustic, or vibratory means. Pheromones are used by most fully aquatic crabs, while terrestrial and semiterrestrial crabs often use visual signals, such as waving their claws to attract mates.
The vast number of brachyuran crabs have internal fertilization and mate belly-to-belly. Females can store the sperm for a long time before using it to fertilize their eggs. When fertilization has taken place, the eggs are released onto the female's abdomen, below the tail flap, secured with a sticky material (as seen on our crab in the photos). In this location, they are protected during embryonic development. Females carrying eggs are called “berried” since the eggs resemble round berries.
When development is complete, the female releases the newly hatched larvae into the water, where they are part of the plankton. The release is often timed with the tidal cycle. The free-swimming tiny zoea larvae can float and take advantage of water currents.
Becoming an Adult Crab is a Crack-Up - Literally!
Once crabs have become juveniles, they still have to keep moulting many more times to become adults. They are covered with a hard shell, which would otherwise prevent growth. The moult cycle is coordinated by hormones. When preparing for moult, the old shell is softened and partly eroded away, while the rudimentary beginnings of a new shell form under it.
At the time of moulting, the crab takes in a lot of water to expand and crack open the old shell at a line of weakness along the back edge of the carapace. The crab must then extract all of itself – including its legs, mouthparts, eyestalks, and even the lining of the front and back of the digestive tract – from the old shell. This is a difficult process that takes many hours, and if a crab gets stuck, it will die. After freeing itself from the old shell (now called an exuvia), the crab is extremely soft and hides until its new shell has hardened. While the new shell is still soft, the crab can expand it to make room for future growth.