Facts: Crustaceans

Summary

Crustaceans, a diverse group of invertebrates with a 540-million-year history, are incredibly successful aquatic animals found in various environments from the Arctic to the Antarctic. They include well-known species like crabs, lobsters, and shrimp, and range from microscopic sizes to the giant Japanese spider crab with a leg span of 13 feet. These cold-blooded creatures possess an exoskeleton made of chitin and calcium carbonate, and use gills for respiration. They exhibit fascinating behaviors like bioluminescence and symbiotic relationships, and some can regenerate lost limbs. Crustaceans face threats from climate change, with species like Antarctic krill experiencing significant population declines due to rising water temperatures.

Takeaways

• 🦐 Crustaceans are incredibly diverse and successful, with a history dating back over 540 million years.
• 🌊 They inhabit a wide range of aquatic environments, from the Arctic to the Antarctic, and even some on land.
• 🦀 The group includes well-known species like crabs, lobsters, shrimp, and crayfish, among tens of thousands of others.
• 🔍 Crustaceans come in a variety of sizes, from microscopic water fleas to the enormous Japanese spider crab with a leg span of up to 13 feet.
• 🦑 They possess an external skeleton made of chitin and calcium carbonate, which provides protection and support.
• 🕷️ Crustaceans have a segmented body with jointed appendages that serve multiple functions, such as movement, feeding, and reproduction.
• 👀 They have compound eyes and a primitive brain, with a simple heart that pumps hemolymph, a fluid similar to vertebrate blood.
• 🌡️ As cold-blooded animals, crustaceans cannot regulate their body temperature and it changes with the environment.
• 💧 Most crustaceans breathe through gills, which can be located in different parts of their body depending on the species.
• 🚶 Crustaceans exhibit various lifestyles, from solitary to swarming, and some even form symbiotic relationships with other marine organisms.
• 🦞 Decapods, which include lobsters, shrimp, and crabs, are the most consumed crustaceans by humans.
• 🦑 Crustaceans can regenerate lost limbs and undergo a process called ecdysis to grow by molting and replacing their exoskeleton.
• 🌱 Chemical signals are crucial for crustaceans during different life stages, aiding in settlement, communication, and reproduction.
• 🧬 Some crustaceans, like barnacles, are hermaphrodites, while others practice internal fertilization and have diverse reproductive strategies.
• ⚠️ Climate change poses a significant threat to crustaceans, as evidenced by the decline of Antarctic krill due to rising water temperatures.

Q & A

How long have crustaceans been around according to the fossil record?

Crustaceans have been around for over 540 million years, as indicated by fossils.

What is the relationship between crustaceans and arthropods?

Crustaceans are a subgroup of tens of thousands of species within the Phylum that contains arthropods.

Where are crustaceans most commonly found?

Crustaceans are most commonly found in the aquatic world, including oceans, rivers, lakes, and streams, with the majority being marine.

Which crustacean is known to live on land?

The coconut crab is an example of a crustacean that can live on land, while woodlice are the only crustaceans that live entirely on land.

What are some extreme environments where crustaceans can be found?

Crustaceans can be found in extreme environments such as ocean trenches deeper than 5.5 miles (9 km) and mountain lakes as high as 3 mi (5 km) above sea level.

What is the size range of crustaceans?

Crustaceans vary greatly in size, with many being microscopic and some of the smallest being water fleas, fairy shrimp, and brine shrimp, which are mostly smaller than a quarter inch (6 mm). The largest is the Japanese spider crab with a leg span of up to 13 ft (4 m).

What is the significance of the exoskeleton in crustaceans?

The exoskeleton provides protection and a rigid framework for muscles to attach, and it is made flexible by a substance called chitin.

How do crustaceans breathe?

Most crustaceans use gills for respiration. In decapods, such as lobsters, the gills are feathery structures located beneath the shell, at the tops of the legs.

What is the process by which crustaceans grow after reaching adulthood?

Crustaceans grow by molting and replacing their exoskeleton with a larger one in a process called ecdysis, which is controlled by hormones.

How do crustaceans reproduce?

In most crustaceans, the sexes are separate, and fertilization is usually internal. Some species protect their eggs by carrying them around, while others release their eggs into the water.

What is the impact of climate change on crustaceans, specifically Antarctic krill?

Climate change, such as rising water temperatures causing ice melt, has led to a significant decline in the numbers of Antarctic krill, which are crucial to the food chain as they are a primary food source for many large animals.