AFS 362 Exam 1-Extra terms and stuff

Crustacean Kingdom

Animalia

Crustacean Phylum

Arthropoda

Crustacean Class

Crustacea

Reptantia

Walkers (crabs, lobsters)

Natantia

Swimmers (shrimp, prawns)

Ecdysis Stages: Premolt or Proecdysis

Stage 1, gradual thinning of cuticle, storage of Ca++ in internal organs and blood, glycogen deposition in dermal tissues

Ecdysis Stages: Molt or Ecdysis

Stage 2, emergence at ecdysial suture, abrupt size increase (swelling) due to osmosis

Ecdysis Stages: Postmolt or Postecdysis

Stage 3, rapid deposition of chitin, Ca++, and other proteins, hardening process

Ecdysis Stages: Stage 4

Instar period (period in between molts)

Deterministic Growth

Some crustaceans (ex. green crab) reach a terminal molt (anecdysis)

Non-Deterministic Growth

Other crustaceans (ex. lobster) keep molting well into old age

X-organ in Molt Cycle

Located in eyestalk, releases MIH (molt inhibitory hormone) which suppresses the Y-organ from releasing α-ecdysone

Y-organ in Molt Cycle

Produces α-ecdysone (molting hormone), suppressed by MIH from X-organ but when MIH levels decrease α-ecdysone is released

Hepatopancreas in Molt Cycle

Hydroxylates (adds -OH group) α-ecdysone to form β-ecdysone, which is the active form that TRIGGERS molting

Mandibular Organ in Molt Cycle

Forms Juvenile Hormone (Methyl farnesoate) that promotes activation of α-ecdysone

Relation of Eyestalks to Molt Cycle

X-organ is located in eyestalks, environmental inputs (light/dark cycle, temperature, stress) trigger x-organ and release of MIH

Eyestalk ablation

Removal of eyestalks (which contain x-organ!) which can trigger rapid molting/maturation

Foregut

Contains esophagus, cardiac stomach, pyloric stomach, and anterior digestive diverticula (diverticula is in close contact with hepatopancreas tissue which generates enzymes and lipid emulsifiers to aid lipid uptake)

Midgut

Contains intestine and digestive diverticula

Hindgut

Contains rectum and tegumental glands

Astaxanthin

Essential dietary pigment/antioxidant for crustaceans (deficiency causes dietary bluing)

Water soluble vitamins

B-complex, C and K

Lipid soluble vitamins

D, E, and A

Chelae (for feeding)

Captures food

Mouth parts for feeding

Maxiliipeds, maxillae, and mandibles

Biofloc

System that utilizes beneficial bacteria to convert waste (ammonia, NH3) into protein rich microbial flocs (food for crustaceans!)

Hormone Cascade System (Molt Cycle, X and Y organs)

Control system for molting, integrates environmental sensing and triggers a series that affects gonad maturation and molting