Lobsters
Introduction.
Lobsters are invertebrates with a hard exoskeleton. Like most arthropods lobsters remove their exoskeleton to grow. This process is called moulting. During this process, some species change their colour. They have eight walking legs. In them the first three pairs have claws. Among them the first pair is much larger. Like other arthropods they show bilateral symmetry. Lobsters’ body is divided into four parts as head, thorax, abdomen and the tail. Head and thorax is covered by a chitinous carapace. Their head consists of antennae, antennule, maxillae and maxilliped. As lobsters basically live in ocean bottom environments antennas on their heads are used as sensors. They have complex eyes. Their abdomen consists of swimmerets and their tail contains uropod and telson.
Same as snails and spiders, lobsters’ blood also in blue colour because their blood contains hemocyanin. Lobsters have an organ called hepatopancreas and it act as their liver and pancreas.
Their lifespan is about 45-50 years. Sometimes the older animals have high fertility than the younger ones. Lobsters need more metabolic energy for their growth. 10%-15% of lobsters die during the process of moulting. According to Guinness World Records the largest lobster that caught yet is reported from Nova Scotia in Canada. It weighs about 20.15Kg(44.4lb).
Behaviour.
Lobsters live in rocky, sandy or muddy environments of bottoms just away from the shoreline of all oceans. Lobsters feed on dead fish, molluscs, crustaceans and worms. Normally lobsters are 25-50cm(1020in) long. They move by walking slowly on the ocean bottom. However, when they sense any danger they swim backward quickly using legs of their abdomen. This is known as caridoid escape reaction.
Importance in fishery industry.
Two species of lobsters are important in Sri Lankan fisheries sector. They are spiny lobster and slipper lobsters. Six species of spiny lobsters are recorded from Sri Lanka. In earlier there were all the six species in the Southern coastline of Sri Lanka. But now there is only five species except Panulirus polyphagus. Nets set on the sea bottom and diving methods are used commonly to catch them. Because of their nocturnal behaviour, the lobsters fishing is done often at night. They are popular as a very tasty dish. Lobster’s whole body or tail area is kept for freezing and then export. At present as their population density is declining rules are implement to conserve them.
Species of lobsters found in Sri Lanka.
Lobsters are invertebrates with a hard exoskeleton. Like most arthropods lobsters remove their exoskeleton to grow. This process is called moulting. During this process, some species change their colour. They have eight walking legs. In them the first three pairs have claws. Among them the first pair is much larger. Like other arthropods they show bilateral symmetry. Lobsters’ body is divided into four parts as head, thorax, abdomen and the tail. Head and thorax is covered by a chitinous carapace. Their head consists of antennae, antennule, maxillae and maxilliped. As lobsters basically live in ocean bottom environments antennas on their heads are used as sensors. They have complex eyes. Their abdomen consists of swimmerets and their tail contains uropod and telson.
Same as snails and spiders, lobsters’ blood also in blue colour because their blood contains hemocyanin. Lobsters have an organ called hepatopancreas and it act as their liver and pancreas.
Their lifespan is about 45-50 years. Sometimes the older animals have high fertility than the younger ones. Lobsters need more metabolic energy for their growth. 10%-15% of lobsters die during the process of moulting. According to Guinness World Records the largest lobster that caught yet is reported from Nova Scotia in Canada. It weighs about 20.15Kg(44.4lb).
Behaviour.
Lobsters live in rocky, sandy or muddy environments of bottoms just away from the shoreline of all oceans. Lobsters feed on dead fish, molluscs, crustaceans and worms. Normally lobsters are 25-50cm(1020in) long. They move by walking slowly on the ocean bottom. However, when they sense any danger they swim backward quickly using legs of their abdomen. This is known as caridoid escape reaction.
Importance in fishery industry.
Two species of lobsters are important in Sri Lankan fisheries sector. They are spiny lobster and slipper lobsters. Six species of spiny lobsters are recorded from Sri Lanka. In earlier there were all the six species in the Southern coastline of Sri Lanka. But now there is only five species except Panulirus polyphagus. Nets set on the sea bottom and diving methods are used commonly to catch them. Because of their nocturnal behaviour, the lobsters fishing is done often at night. They are popular as a very tasty dish. Lobster’s whole body or tail area is kept for freezing and then export. At present as their population density is declining rules are implement to conserve them.
Species of lobsters found in Sri Lanka.
- Panulirus homarus
- FAO name : En- scalloped spiny lobster.
- Local name : “S-welissa”.
- Size : maximum length of the body is 32cm. length of the head is 12cm.
- Panulirus longipes
- FAO name : En-long legged spiny lobster.
- Local name : -
- Size : maximum length of the body is 30cm. length of the head is 12cm.
- Panulirus ornatus
- FAO name : En- Omate spiny lobster.
- Local name : “S-diwissa”.
- Size : maximum length of the body is 50cm.
- Panulirus penicillatus
- FAO name : En- Pronghorn spiny lobster.
- Local name : “S-galissa”.
- Size : maximum length of the body is 40cm.
- Panulirus polyohagus
- FAO name : En- Mud spiny lobster.
- Local name : -
- Size : maximum length of the body is 40cm.
- Panulirus versicolor
- FAO name : En- Painted spiny lobster
- Local name : “S-rajaissa”.
- Size : maximum length of the body is 40cm
- Panulirus sewelli
- FAO name : En- Arabian whip lobster.
- Local name : -
- Size : maximum length of the body is 20cm.
- Parribacusus antarcticus
- FAO name : En- Sculptured mitten lobster.
- Local name : -
- Size : maximum length of the body is 20cm. length of the head is 9cm.
- Scyllarus martensii
- FAO name : En- triated locust lobster.
- Local name : -
- Size : maximum length of the body is 6cm. length of the head is 2cm.
- Thenus orientails
- FAO name : En- Flathead lobster.
- Local name : -
- Size : maximum length of the body is 25cm. length of the head is 8cm.
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