LIFE CYCLE OF CRAY FISH

Blue Crayfish Rusty Crayfish

Contents Introduction Distribution and habitat Morphology of Cray fish Procambarus clarkii (Red Swamp Cray Fish) Contents Introduction Distribution and habitat Morphology of Cray fish Sexual dimorphism Collection of brood stock Life cycle of Cray fish -Life cycle -Mating behavior -Fertilization and spawning -Hatching -molting and Growth

Introduction Cray fishes are fresh water cousins of lobsters Taxonomic Position Phylum - Arthropoda, Class- Crustacea, Order- Decapoda, Super family- Astacoidea / Parastacoidea. FW crayfish include 3 families comprising more than 500 species Common names: Crayfish, crawfish, or crawdads , mudbugs, yabbies, lobsters etc  

Distribution & Habitat Distributed around the world from the tropics to the polar regions. Found in swamps, streams, and lakes. They will often conceal themselves under rocks or logs to hide from predators or to ambush prey. They are most active at night, feeds on snails, algae, insect larvae, worms, tadpoles etc. They will also eat decaying plant matter and debris.

Morphology (cont…) Crayfish are usually brown, red or off-white in color They have a distinctive pair of pincers which are useful as a defense mechanism and for finding food.

Sexual dimorphism in Crayfishes

The Northern Cray fish (Orconectes virilis) female male

Sexual dimorphism (cont…) Males Females 1) Openings at the base of the third and fourth pair of walking legs Seminal receptacle is absent Petesma present At the fifth pair of walking legs Possess seminal receptacle for holding the sperm after mating Presence of Thelycum

Collection of brood stock Wild crawfish are harvested with baited traps in the Spring

Collection methods and Implements used

Life cycle of crayfish

Life cycle of Crayfish Adult molting male female Open water mating Young ones detached from mother spermatozoa Female receptacle ovary Stored spermatozoa eggs Young ones on mother’s body burrows fertilization Fertilized egg hatching spawning

Life cycle (cont…) Refers to the tracking of the development of the crayfish from its birth as an egg through it maturing into an adult fish. The crayfish has a life span of two years and its life cycle is, therefore, fairly accelerated.

Mating Behavior Adult crayfish mate in open water and this is usually in late spring or early summer. The female of the species is known to mate with more than one male. The male’s sperm is stored in a receptacle on the female’s underside during mating.

Fertilization and spawning Female makes a burrow in wet soil (the burrow is usually near the water’s edge), in which she will spawn . While the female is building her burrow, the eggs in the ovary develop and are ready for release through the oviducts. The sperm which was stored earlier will fertilize the newly released eggs and they become attached to the swimmerets which are found on the underside of the female’s tail, until they hatch. A female may lay 10 to 800 dark brown eggs. Not all the eggs that are released get fertilized; this is dependent on the size of the sperm.

Hatching The burrow will hold water and it helps to maintain the eggs and crayfish moist Crayfish eggs have an incubation period of around three weeks This is dependent on ambient temperature with 74˚F being recommended as the optimal temperature. The crayfish eggs hatch and the hatchlings continue to stay attached to the mother fish’s swimmerets for a few more weeks.

Cont… Hatching will takes place in the burrow itself No larval stages. Eggs will hatch in to tiny Cray fishes After the hatching, with her brood still attached, the female emerges from the burrow to find food. The female is known to eat the hatchlings if she stays on in the burrow and food becomes an issue. Once the fish is in open water, the chances of the hatchlings detaching from the mother increase dramatically

Molting and growth Another important stage in the crayfish lifecycle is the molting stage. This is when the juvenile fish shed its hard exoskeleton to make room to grow. This can be a frequent exercise during the growth period. It is important to note that the rate of growth of crayfish juveniles is greatly impacted by variations in the environment.  This includes: 1. Water temperature 2. Population size 3. Amount of food available 4. Dissolved oxygen level in the water

Cont… Typically, a crayfish molts about 11 times before reaching sexual maturity; this takes about one year 0r 6-8 months. A crayfish that reaches sexual maturity will stop growing. They will have the distinctive darker coloring and larger pincers associated with maturity and they shows sexual dimorphism. At this point, the adult fish are ready to start the crayfish life cycle all over again.