Questions and Problems 1. Name the appendages of the crayfish and give their fun

Question

Questions and Problems 1. Name the appendages of the crayfish and give their functions 2. We noted that modern researchers have isolated the genes coding for spider silk protein. So what? What, if anything, can they do with that knowledge. Explain your answer fully 3. Crayfish reproduction involves copulation wherein a male transfers sperm to the seminal receptacle of the female. In most species, esg-laying follows immediately after and the esgs are fertilized as they are released. The fertilized eggs are deposited by the females on her swimmerets where they are sheltered and aerated until they hatch into tiny crayfish which adopt the same niche as their parents. In many marine crabs the female actually holds the sperm for some time before producing eggs and then often fertilizes them within her body internal fertilization). The marine crab eggs hatch into larval stages which are adapted to the pelagic niche. These larvae are members of the marine plankton community for weeks or months before they undergo a final molt to assume the adult morph and niche. What is the evolutionary (adaptive) significance of larval stages which have niche requirements different from their parents?

Explanation / Answer

1. There are about more than 10 appendages in crayfish. These include antennules, antenna, mandible or jaw, first maxilla, second maxilla, first maxilliped, second maxilliped, third maxilliped, cheliped, walking leg, swimmeret, uropod and telson.

Antennules: It is located in fronnt of mouth. It's function is to sense of touch & taste and helps crayfish to maintain balance.

Antenna: It is located in fronnt of mouth. It's function is to sense of touch & taste.

Mandible or jaw: it is located in mouth. It helps to crush the food.

First maxilla: It is located behind mandibles. It moves food to the mouth.

Second maxilla: It is located behind mandibles. It moves water in gill chamber.

First maxilliped: it is located in ventral and forward part of thorax region. It holds the food and helps in senses the touch and taste of the food.

Second maxilliped: it is located in ventral and forward part of thorax region. It holds the food and helps in senses the touch and taste of the food.

Third maxilliped: it is located in ventral and forward part of thorax region. It holds the food and helps in senses the touch and taste of the food.

Cheliped: it is located in ventral part of thorax posterior to maxillipeds. It grasps the food.

Walking leg: it is located in ventral part of thorax posterior to maxillipeds and helps in locomotion.

Swimmeret: It is located in abdominal region on ventral side. The 1st swimmeret in males trasfers the sperms to female. In females 2nd to 5th swimmerets help in holding eggs and young and also helps in locomotion.

Uropod: it is located at posterior end or at tail end. It helps in swimming.

Telson: it is located at posterior end or at tail end. It helps in swimming.

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