Decapoda
Decapoda is an order of crustaceans that includes familiar animals like crabs, lobsters, crayfish, and shrimp. This order comprises around 15,000 species, making it the largest order within the class Malacostraca and one of the most diverse groups of living organisms. Decapods are found in nearly every aquatic habitat on Earth, from the deep sea to freshwater streams and even terrestrial environments.
Characteristics
Decapods are characterized by their ten walking legs, which give them their name (from the Greek words deka meaning ten and pous meaning foot). These legs are typically paired, with the first pair often modified into large claws used for defense, predation, and manipulating food. They also have a hard exoskeleton, a segmented body with three distinct regions (cephalothorax, abdomen, and telson), and two pairs of antennae.
Environments
Decapods have adapted to a wide range of environments. Most species are marine, living in coastal waters, the open ocean, and even deep-sea hydrothermal vents. Some species have evolved to live in freshwater habitats, including rivers, lakes, and swamps. A few decapods, like the coconut crab, have even become terrestrial, spending their lives on land.
Common Names
Decapods are known by a variety of common names, depending on their morphology and habitat. Some of the most familiar names include:
- Crabs: These are typically broad and flat, with a wide carapace and small abdomens. They are often found on the seafloor or in intertidal zones.
- Lobsters: These are elongated, with large claws and a segmented abdomen. They are often found in deeper waters.
- Crayfish: These are freshwater relatives of lobsters, often found in streams, rivers, and lakes.
- Shrimp: These are smaller, more slender decapods with long, thin antennae. They are often found in shallow waters and are a popular food source.
References
For further information on Decapoda, consult these reliable sources: