Blue Crab Life CycleBlue Crab Life Cycle

Create by Dave WernerCreate by Dave WernerMATESMATES

website of information:website of information:http://www.blue-crab.org/http://www.blue-crab.org/

lifecycle.htmllifecycle.html

Mating Mating

• Female blue crabs mate only once in their lives Female blue crabs mate only once in their lives • immediately following the last molt, the female is known as immediately following the last molt, the female is known as

a "sook.“a "sook.“• females release a pheromone in their urine which attracts females release a pheromone in their urine which attracts

males. males. • Male crabs vie for females and will carry and protect them, Male crabs vie for females and will carry and protect them,

called "cradle carrying," until molting occurs called "cradle carrying," until molting occurs • when the female's shell is soft, the pair will mate when the female's shell is soft, the pair will mate • the female captures and stores the male's sperm in sac-like the female captures and stores the male's sperm in sac-like

receptacles so that she can fertilize her eggs at a later time receptacles so that she can fertilize her eggs at a later time • Once the female's shell has hardened, the male will release Once the female's shell has hardened, the male will release

her and she will migrate to higher salinity waters to spawn. her and she will migrate to higher salinity waters to spawn.

Spawning Spawning

• After mating, females migrate to After mating, females migrate to high-salinityhigh-salinity waters in waters in lower estuaries, sounds, and near-shore spawning areas.lower estuaries, sounds, and near-shore spawning areas.

• They over-winter before spawning by burrowing in the mud. They over-winter before spawning by burrowing in the mud. • Most females spawn for the first time Most females spawn for the first time two to nine monthstwo to nine months

after mating, usually from May through August the after mating, usually from May through August the following season. following season.

• The female extrudes fertilized eggs into a cohesive mass, The female extrudes fertilized eggs into a cohesive mass, or "or "spongesponge," that remains attached to her ," that remains attached to her abdomenabdomen until until the larvae emerge. the larvae emerge.

• The average sponge contains about The average sponge contains about two million eggstwo million eggs and and is formed in about two hours. is formed in about two hours.

• Christmas Crab Video – Youtube• Christmas Island Crabs – Youtube

Growth Stages Growth Stages

• Growth and development of the blue crab, as in Growth and development of the blue crab, as in other crustaceans, consist of a series of other crustaceans, consist of a series of larval, larval, juvenile, and adult stagesjuvenile, and adult stages during which a during which a variety of morphological, behavioral, and variety of morphological, behavioral, and physiological changes occur. These changes are physiological changes occur. These changes are most dramatic when the animal molts (sheds its most dramatic when the animal molts (sheds its rigid exoskeleton) permitting growth and changes rigid exoskeleton) permitting growth and changes in body shape. in body shape.

• Before molting, a new shell is formed Before molting, a new shell is formed underneath the old exoskeletonunderneath the old exoskeleton, which then , which then loosens and is cast off. The new shell is initially loosens and is cast off. The new shell is initially softsoft, but it expands and , but it expands and hardens in a few hourshardens in a few hours. .

• The stage between molts is termed The stage between molts is termed intermoltintermolt..

Stage 1 – Zoeae Stage 1 – Zoeae Table 7.37p.142 or p.135 Table 7.37p.142 or p.135

• First stage larvae, called First stage larvae, called zoeaezoeae, measure approximately , measure approximately 0.25 mm0.25 mm at hatching. at hatching.

• They bear little morphological resemblance to adultsThey bear little morphological resemblance to adults (Hopkins 1943), are (Hopkins 1943), are filter feedersfilter feeders, and live a , and live a planktonicplanktonic existence in the existence in the high-salinityhigh-salinity surface waters near the surface waters near the spawning grounds (Pyle and Cronin 1950; Darnell 1959).spawning grounds (Pyle and Cronin 1950; Darnell 1959).

• Tagatz (1968) found more zoeae near the water's surface Tagatz (1968) found more zoeae near the water's surface than at the bottom. Evidence suggests that blue crab zoeae than at the bottom. Evidence suggests that blue crab zoeae hatch in the Chesapeake Bay, Chincoteague Bay, Delaware hatch in the Chesapeake Bay, Chincoteague Bay, Delaware Bay, and other estuaries and drift out to sea, where they Bay, and other estuaries and drift out to sea, where they feed and grow. feed and grow.

• These larvae may These larvae may migrate verticallymigrate vertically in the water column in the water column to reach flood and ebb tides, which transport them back to reach flood and ebb tides, which transport them back into the bay area.into the bay area.

Stage 1 – Zoeae ContinuedStage 1 – Zoeae Continued

• The zoeae and all subsequent life stages The zoeae and all subsequent life stages can increase body size only by can increase body size only by moltingmolting (Hay 1905; Pyle and Cronin 1950). Zoeal (Hay 1905; Pyle and Cronin 1950). Zoeal development may require development may require 31 to 49 days31 to 49 days, , depending on depending on salinitysalinity and and temperaturetemperature, , but development time has been shown to but development time has been shown to be variable even in a single salinity-be variable even in a single salinity-temperature regime (Williams 1965). temperature regime (Williams 1965).

• Zoeae molt Zoeae molt four to sevenfour to seven times before times before entering the next stage of development. entering the next stage of development.

• The final zoeal stage is about The final zoeal stage is about 1.0 mm1.0 mm in in width (Hopkins, Rogers 1944).width (Hopkins, Rogers 1944).

Stage 2 - Megalops Stage 2 - Megalops

• The The final moltfinal molt of the zoeae is characterized by a conspicuous of the zoeae is characterized by a conspicuous change to the second larval stage, called a change to the second larval stage, called a megalopsmegalops (also (also termed megalopa [singular] or megalopae [plural]. termed megalopa [singular] or megalopae [plural].

• Development to this stage requires Development to this stage requires 31 to 49 days31 to 49 days. The . The megalops larva is more megalops larva is more crablikecrablike in appearance than the in appearance than the zoeae, its carapace is broader in relation to its length, and has zoeae, its carapace is broader in relation to its length, and has biting clawsbiting claws and pointed joints at the ends of the legs. and pointed joints at the ends of the legs.

• It measures about It measures about 1.0 mm1.0 mm in width. The megalops in width. The megalops swims swims freelyfreely, but generally stays near the bottom in nearshore or , but generally stays near the bottom in nearshore or lower-estuarine, lower-estuarine, high-salinityhigh-salinity areas (Tagatz, 1968). The areas (Tagatz, 1968). The megalops stage lasts megalops stage lasts 6 to 206 to 20 days days, after which the megalops , after which the megalops molts into the "molts into the "first crabfirst crab" stage, with proportions and " stage, with proportions and appearance more like those of an appearance more like those of an adultadult..

• There are usually There are usually seven zoeal stagesseven zoeal stages and one and one postlarvalpostlarval, , or or megalopalmegalopal, stage. On occasion, an eighth zoeal stage is , stage. On occasion, an eighth zoeal stage is observed.observed.

Juveniles Juveniles

• The juvenile "The juvenile "first crabfirst crab" is typically " is typically 2.5 mm2.5 mm wide (from tip to tip wide (from tip to tip of the lateral spines of the carapace). of the lateral spines of the carapace).

• These juveniles gradually migrate into shallower, These juveniles gradually migrate into shallower, less-salineless-saline waters in upper estuaries and rivers where they grow and mature waters in upper estuaries and rivers where they grow and mature (Fischler and Walburg 1962). (Fischler and Walburg 1962).

• Van Engle (1958) and Tagatz (1968) reported that many juveniles Van Engle (1958) and Tagatz (1968) reported that many juveniles had completed this migration had completed this migration by fall and early winterby fall and early winter. New . New evidence, however, suggests the bulk may not reach the upper evidence, however, suggests the bulk may not reach the upper parts of tributaries and Chesapeake Bay until the following parts of tributaries and Chesapeake Bay until the following summer.summer.

• Males generally migrate farther upstream, preferring low-salinity Males generally migrate farther upstream, preferring low-salinity waters, whereas females tend to stay in lower rivers and estuaries waters, whereas females tend to stay in lower rivers and estuaries (Dudley and Judy 1971; Music 1979).(Dudley and Judy 1971; Music 1979).

• Molting and growing stop during winterMolting and growing stop during winter (Churchill, 1921; (Churchill, 1921; Darnell 1959); growth resumes as waters warm, and juveniles Darnell 1959); growth resumes as waters warm, and juveniles generally reach maturity during the spring or summer of the year generally reach maturity during the spring or summer of the year following their hatching. following their hatching.

AdultsAdults

• sexual maturity is reached after 18 sexual maturity is reached after 18 to 20 postlarval molts, at the age of to 20 postlarval molts, at the age of 1 to 1½ years 1 to 1½ years

• Males continue to molt and grow Males continue to molt and grow after they reach sexual maturity after they reach sexual maturity

• females cease to molt and grow females cease to molt and grow (terminal molt) when they mature (terminal molt) when they mature and mate and mate

Why do females stop Why do females stop molting?molting?

Is there an advantage to Is there an advantage to this???this???

AnswerAnswer

• Molting takes Molting takes energyenergy; energy that is better ; energy that is better used for used for reproductive outputreproductive output. Since it . Since it takes more energy to produce eggs, the takes more energy to produce eggs, the theory is that mature female crabs don't theory is that mature female crabs don't grow as large or molt as frequently because grow as large or molt as frequently because of their of their reproductive energeticsreproductive energetics. .

• The converse is that The converse is that sperm production is sperm production is cheapcheap, so males don't put energy into , so males don't put energy into reproduction, rather they put it into reproduction, rather they put it into somatic growth. somatic growth.

Other molting theories…Other molting theories…

• Molting is Molting is energy dependentenergy dependent. Larger . Larger animals must store far more animals must store far more nutrientsnutrients for for molting than do smaller juveniles. Thus, a molting than do smaller juveniles. Thus, a really big lobster only molts every really big lobster only molts every 2 to 5 to 2 to 5 to 10 years10 years. Similarly for blue crabs, . Similarly for blue crabs, the the larger the crab, the more difficult to larger the crab, the more difficult to store energy for moltingstore energy for molting. .

• Molting is Molting is risky businessrisky business. Larger animals . Larger animals may be at more risk, hence, they are not may be at more risk, hence, they are not frequent in the population. frequent in the population.

Where do they go as adults?Where do they go as adults?

• After the females mate and migrate to spawning areas, After the females mate and migrate to spawning areas, they either they either remainremain there for the rest of their lives or move there for the rest of their lives or move only short distances out to sea. only short distances out to sea.

• In In warmerwarmer months, males generally stay in months, males generally stay in low-salinitylow-salinity waters such as creeks, rivers, and upper estuaries.waters such as creeks, rivers, and upper estuaries.

• Research on blue crabs in the Chesapeake Bay indicated Research on blue crabs in the Chesapeake Bay indicated that females over-wintered at the that females over-wintered at the mouthmouth of the bay and of the bay and spawned there in spring, whereas the migration of spawned there in spring, whereas the migration of males males was non-directionalwas non-directional. .

• Crabs bury Crabs bury themselves in mud in winterthemselves in mud in winter and emerge and emerge when temperatures rise in when temperatures rise in springspring. .

• The maximum The maximum ageage for most blue crabs in the Mid-Atlantic for most blue crabs in the Mid-Atlantic Region is Region is three yearsthree years; adults thus live an average of less ; adults thus live an average of less than one year after reaching maturity.than one year after reaching maturity.

Autotomy & Regeneration Autotomy & Regeneration

• Blue crabs have the ability to Blue crabs have the ability to sacrifice limbssacrifice limbs (called (called autotomyautotomy) ) in order avoid capture. Missing limbs in order avoid capture. Missing limbs are regrown by a process called are regrown by a process called regenerationregeneration..

• See See http://www.blue-crab.org/autotomy.html for detailed information. for detailed information.

Video ClipsVideo Clips

•Deadliest Catch - How Crab Pots Work

•Rabid Crab Pots

TaxonomyTaxonomy• Superkingdom:Superkingdom:EukaryotaAll animals, plants, fungi, and protists.All animals, plants, fungi, and protists.• Kingdom:Kingdom:AnimaliaAnimals.Animals.• Subkingdom:Subkingdom:MetazoaMulticellular animals.MetazoaMulticellular animals.• Phylum:Phylum:ArthropodaJointed leg invertebrates.ArthropodaJointed leg invertebrates.• Subphylum:Subphylum:CrustaceaHaving a crustlike shell.CrustaceaHaving a crustlike shell.• Class:Class:MalacostracaShrimps, Crabs, Lobsters.MalacostracaShrimps, Crabs, Lobsters.• Subclass:Subclass:EumalacostracaHave a 5-8-6 (head-thorax-abdomen) segment body plan.EumalacostracaHave a 5-8-6 (head-thorax-abdomen) segment body plan.• Superorder:Superorder:EucaridaCharacterized by having the carapace fused to all thoracic segments, EucaridaCharacterized by having the carapace fused to all thoracic segments,

and by the possession of stalked eyes.and by the possession of stalked eyes.• Order:Order:DecapodaTen legs.DecapodaTen legs.• Suborder:Suborder:PleocyemataGills lacking secondary branches and eggs carried on pleopods PleocyemataGills lacking secondary branches and eggs carried on pleopods

before hatching.before hatching.• Infraorder:Infraorder:BrachyuraTrue crabs. Characterized by a reduced abdomen, folded beneath the BrachyuraTrue crabs. Characterized by a reduced abdomen, folded beneath the

cephalothorax, and inserted between the pereiopods or in a special cavity, which prevents it cephalothorax, and inserted between the pereiopods or in a special cavity, which prevents it from impeding movements.from impeding movements.

• Section:Section:EubrachyuraPress-button holding system, consisting of a prominence always on the EubrachyuraPress-button holding system, consisting of a prominence always on the fifth sternite and a socket always positioned on the sixth abdominal segment. Prevents fifth sternite and a socket always positioned on the sixth abdominal segment. Prevents abdomen from moving.abdomen from moving.

• Subsection:Subsection:HeterotremataGroup in which the genital openings of the males are on the HeterotremataGroup in which the genital openings of the males are on the appendages and those of the females are on the thorax.appendages and those of the females are on the thorax.

• Superfamily:Superfamily:Portunoidea Portunoidea • Family:Family:PortunidaeSwimming crabs.PortunidaeSwimming crabs.• Subfamily:Subfamily:Portuninae Portuninae • Genus:Genus:CallinectesGreek word for beautiful swimmer (Calli = beautiful, Nectes = swimmer).CallinectesGreek word for beautiful swimmer (Calli = beautiful, Nectes = swimmer).• Species:Species:SapidusLatin word for savory.SapidusLatin word for savory.• Scientific name:Scientific name:Callinectes sapidusCallinectes sapidus