Crabs go through several larval stages before settling on the ocean floor or intertidal zones.
True crabs have 10 legs and a symmetrical abdomen fully tucked under the carapace, while non-true crabs have differently shaped abdomens and modified appendages.
Rearing crabs in captivity is challenging due to the specific nutrient requirements, molting seasons, and difficulties in capturing crabs at the right stage for harvesting.
Deep dives
Crabs go through multiple larval stages before becoming fully developed
Crabs start as eggs inside the mother and go through several larval stages before settling on the ocean floor or intertidal zones. The final larval stage, known as a mega lopa, closely resembles the adult crab. The larval stages differ among different crustaceans, with some species skipping certain stages. The larvae primarily feed on plankton and are vulnerable to predation. They molt as they grow, shedding their exoskeletons in order to expand. Molting is driven by internal growth and organ pressure on the exoskeleton. Molting may occur seasonally for some crab species, and during this time, fishing for them is prohibited.
Not all crabs are true crabs
A true crab, or brachyuran, has 10 legs and a symmetrical abdomen fully tucked under the carapace. There are also non-true crabs, or anomurans, that have differently shaped abdomens and may have reduced or modified appendages. Anomurans include creatures like hermit crabs and squat lobsters. King crabs, often sought after for culinary purposes, are actually anomurans and not true crabs. This distinction is based on morphological traits and is useful for classification purposes.
Challenges in rearing crabs in captivity
Efforts to rear crabs in captivity for commercial or research purposes have generally been unsuccessful. Rearing crabs through their full life cycle, especially the larval stages, poses challenges such as providing the correct nutrients and environmental conditions. Some species have specific molting seasons, and capturing crabs at the right stage is essential for harvesting. In the case of coconut crabs, they have not been successfully reared in captivity, limiting their availability for commercial purposes.
Coconut Crabs: Nature's Elegant Solution to a Problem
Coconut crabs, also known as robber crabs, are the largest land-dwelling arthropods and have unique behaviors such as stealing shiny objects. Initially thought to be a new species, they are actually the largest hermit crabs in the world. Starting their lives in the ocean, they eventually move to land where they have hardened and straightened abdomens. With their massive pinching force, coconut crabs can tear apart coconuts and even drag around objects weighing up to 60 pounds. Although they taste delicious and have been eaten by humans, their numbers have significantly decreased due to overconsumption.
The Fascinating World of Crabs: From Predators to Bottom Feeders
Crabs exhibit a wide range of behaviors and diets. While some are bottom feeders or scavengers, eating poop and dead animals, others are skillful predators. One such example is the shame-faced crab, known for its hunting ability and its special claw adapted to break through the shells of gastropod snails. Different crab species vary in speed, with some being very fast, like the blue crab, others are slower. Crab behavior and physical characteristics are influenced by environmental factors, such as oxygen levels, with crustaceans being larger in water due to more efficient respiratory systems.
Claw hands! Beady eyes! Pinching forces that could crack your skull! Gentleman, scholar, curator of the Natural History Museum’s crustacea collection and Carcinologist Adam Wall takes us on a tour of the museum’s crab bunker to discuss everything from the tiniest to the most hauntingly giant crabs, discovering new species, crabs that are NOT crabs, sea monkeys, hairy crabs, hermit crabs, crab dongs, crab butts, crab butters, the secret history of secret Maryland spices, Amelia Earhart rumors, giant invasive crabs in Norway, behind the scenes Hollywood crabs, and so much more. So dazzling and comprehensive and weird – we had to crack this episode in two. Make sure to catch next week’s.
