Crayfish are freshwater crustaceans found globally in diverse aquatic environments like ponds, streams, and marshes. These bottom-dwelling creatures are characterized by their hard exoskeletons, prominent claws, and segmented bodies, typically ranging from a few centimeters to over 15 centimeters. They are omnivorous scavengers, consuming a varied diet of plants, insects, snails, and decaying organic matter.
Do Crayfish Lay Eggs?
Crayfish lay eggs. A female crayfish carrying eggs is called “berried,” a term from the egg cluster’s berry-like appearance. The female meticulously attaches these eggs to her swimmerets, small, leg-like appendages on her abdomen’s underside. This attachment provides maternal care, protecting and aerating the eggs.
Eggs are small and round, changing color as they develop, from dark (often black) to lighter shades like brownish or yellowish. The number of eggs a female lays can vary significantly, from a few dozen to over 700, depending on her species, size, and health.
The Reproductive Process
Crayfish reproduction often begins in late summer or fall, though some species also breed in spring. During mating, the male uses his antennules for identification and may approach the female aggressively. He clamps the female, often turning her onto her back, to deposit a sperm packet (spermatophore) into a seminal receptacle on her underside. This internal fertilization transfers sperm directly to the female.
After mating, the female can store sperm for several months until she is ready to lay her eggs. When egg-laying commences, the female cleans her abdomen and releases a sticky, gelatinous substance called glair. She curls her abdomen forward, forming a brood chamber, and extrudes her eggs through her gonopores. As the eggs pass over the stored sperm, they are fertilized and carefully attached to her swimmerets by a filament or stalk formed from the glair. The female diligently cares for these attached eggs by rhythmically moving her pleopods for oxygenation and to keep them free from debris.
From Egg to Juvenile
Once attached, eggs incubate for several weeks to a few months, depending on species and water temperature. Unlike many crustaceans, crayfish hatch as miniature adults, not distinct larval forms.
Newly hatched crayfish remain attached to their mother, often by specialized hooks or a telson filament. This attachment provides continued protection and allows further development. They may stay connected for several weeks, undergoing one or two molts under her care.
The mother may secrete pheromones encouraging young to stay close and deterring cannibalism. After these initial molts, young crayfish become fully independent juveniles, growing rapidly through a series of molts, shedding their exoskeletons.