About Crayfish?

Question

How can you tell a female from a male (crayfish)?
What is the anthropod?...

Answer 1

You cannot unless one is egg bound.

Anthropods are any of numerous invertebrate animals of the phylum Arthropoda, including the insects, crustaceans, arachnids, and myriapods, that are characterized by a chitinous exoskeleton and a segmented body to which jointed appendages are articulated in pairs.

Answer 2

Arthropods (Phylum Arthropoda, from the Greek ἄρθρον, meaning joint and ποδός, meaning foot) are the largest phylum of animals and include the insects, arachnids, crustaceans, and others. More than 80% of described living animal species are arthropods [1], with over a million modern species described and a fossil record reaching back to the late proterozoic era. Arthropods are common throughout marine, freshwater, terrestrial, and even aerial environments, as well as including various symbiotic and parasitic forms. They range in size from microscopic plankton (~¼ mm) up to forms several metres long. The largest living arthropod is the Japanese spider crab, with a leg span up to 3½ m (12 ft), and some prehistoric arthropods were even larger, such as Pterygotus and Arthropleura.

Arthropods are characterised by the possession of a segmented body with appendages on each segment. They have a dorsal heart and a ventral nervous system. All arthropods are covered by a hard exoskeleton made of chitin, a polysaccharide, which provides physical protection and resistance to desiccation. Periodically, an arthropod sheds this covering when it moults.

Crayfish

The male is easily distinguished from the female by the presence of a pair of modified first swimmerets called gonopods, which are enlarged and directed forward. These structures are used by the male to transfer sperm to the female. Note also the small openings to each vas deferens at the bases of the fifth pairs of walking legs (the right leg of this specimen has been removed). The vasa deferentia conduct sperm from the testes to the outside of the crayfish. On the female crayfish observe the opening to the seminal receptacle (which receives sperm from the male) as well as the openings to the oviducts at the bases of the third pairs of walking legs.

Answer 3

Crayfish, also called crawfish or crawdad, are closely related to the lobster. More than half of the more than 500 species occur in North America, particularly Kentucky (Mammoth Cave) and Louisiana in the Mississippi basin. Crayfish also live in Europe, New Zealand, East Asia and throughout the world, including the Tristan da Cunha Islands. Nearly all live in freshwater, although a few survive in salt water. Crayfish are characterised by a joined head and thorax, or midsection, and a segmented body, which is sandy yellow, green, or dark brown in colour. The head has a sharp snout, and the eyes are on movable stalks. Crayfish are usually about 7.5 cm (3 inches) long.

The crayfish is typical of most shrimplike crustaceans and is characterised by a joined head and thorax, or midsection, and a segmented body, which is sandy yellow, green, white, pink or dark brown in colour.

Crayfish are usually about 7.5 cm (3 inches) long. Among the smallest is the 2.5-centimetre-long Cambarellus diminutus of the south-eastern United States. Among the largest is Astacopsis gouldi of Tasmania; its length may reach 40 cm and its weight about 3.5 kg (8 pounds).

The head has two pairs of sensory antennae and a pair of eyes on movable stalks. The appendages, or pereiopods, of the thorax include four pairs of walking legs which, as well as walking, are to probe cracks and crevices between rocks looking for food. Crayfish also own one pair of clawbearing chelipeds, which it extends in front of its body while moving. These strong pinchers are specialised for cutting, capturing food, attack, and defence. A pinch can hurt! The crayfish also has several pairs of specialised food handling "legs," bailers to cycle water over the gills, and five pairs of swimmerets which are under the abdomen. All of these "legs" can be regenerated if broken off.

Crayfish have a hard outside skeleton. This jointed exoskeleton provides protection and allows movement, but limits growth. As a result, the crayfish regularly gets too big for its skeleton, sheds it, and grows a new larger one. This is called molting. and occurs six to ten times during the first year of rapid growth, but less often during the second year. For a few days following each molt, crayfish have soft exoskeletons and are more vulnerable to predators.

The male is easily distinguished from the female by the presence of a pair of modified first swimmerets called gonopods, which are enlarged and directed forward. These structures are used by the male to transfer sperm to the female. Note also the small openings to each vas deferens at the bases of the fifth pairs of walking legs (the right leg of this specimen has been removed). The vasa deferentia conduct sperm from the testes to the outside of the crayfish. On the female crayfish observe the opening to the seminal receptacle (which receives sperm from the male) as well as the openings to the oviducts at the bases of the third pairs of walking legs.

insects, crustaceans, spiders, scorpions, and centipedes. There are far more species of arthropods than species in all other phyla combined, and the number of undescribed species in the largest assemblage of arthropods, the insects, probably numbers in the tens of millions. Members of the phylum have been responsible for the most devastating plagues and famines mankind has known. Yet other species of arthropods are essential for our existence, directly or indirectly providing us with food, clothing, medicines, and protection from harmful organisms.