85
South Africa it is found, on muddy or sandy substrates, sometimes with coral fragments; off Madagascar it has been reported from a rocky substrate. It is distributed
in Indo-West Pacific region: East coast of Africa from (Mozambique) to (Natal,
South Africa), south east Madagascar. Off south east Africa the species is taken by
trawlers, while off Madagascar, lobster pots were used during experimental fishing
(Holthuis 1991).
2.3.2 Freshwater Lobsters (Crayfish)
2.3.2.1 General Information About Crayfish
Crayfish are freshwater crustaceans resembling small lobsters (to which they are
related). They are also known as crawfish, crawdads, freshwater lobsters, mountain
lobsters, mudbugs, or yabbies. Taxonomically, they are members of the super families Astacoidea and Parastacoidea. They breathe through feather-like gills. Some
species are found in brooks and streams where fresh water is running, while others
thrive in swamps, ditches, and paddy fields. Most crayfish cannot tolerate polluted
water, although some species such as Procambarus clarkii are hardier. Crayfish feed
on animals and plants, either living or decomposing, and detritus. The name “crayfish” comes from the old French word escrevisse. Some kinds of crayfish are known
locally as lobsters, crawdads, mudbugs, and yabbies. In the Eastern United States,
“crayfish” is more common in the north, while “crawdad” is heard more in central
and southwestern regions. In Australia (on the eastern seaboard), New Zealand and
South Africa, the term crayfish or cray generally refers to a saltwater spiny lobster,
of the genus Jasus that is indigenous to much of southern Oceania. In Singapore, the
term crayfish typically refers to Thenus orientalis, a seawater crustacean from the
slipper lobster family (Wikipedia 2019a).
Because of its important ecological role in freshwater ecosystems, crayfish have
been called a keystone species. The impact of these crustaceans on ecosystems is
more important than expected given their relative abundance or total biomass.
Because these species are both prey and predators, they have a central position in
the food chains of the ecosystem (Geiger et al. 2005).
Biology of Crayfish
Crayfish are found in freshwater environments such as lakes, dams, rivers, and irrigation canals ranging from sea level to sub-alpines. They can be found in most
substrate types. Larger populations are found in areas where there are shelters, and
low pollution, and no predators. Although crayfish are mainly a night animal, some
crayfish are observed during the day, especially in dark waters that provide little
protection from predators (Hollows 2016). Crayfish usually are seen in the darkness
of the evening and morning or at night. During the day they are hiding in pits or
2.3 Lobsters
South Africa it is found, on muddy or sandy substrates, sometimes with coral fragments; off Madagascar it has been reported from a rocky substrate. It is distributed
in Indo-West Pacific region: East coast of Africa from (Mozambique) to (Natal,
South Africa), south east Madagascar. Off south east Africa the species is taken by
trawlers, while off Madagascar, lobster pots were used during experimental fishing
(Holthuis 1991).
2.3.2 Freshwater Lobsters (Crayfish)
2.3.2.1 General Information About Crayfish
Crayfish are freshwater crustaceans resembling small lobsters (to which they are
related). They are also known as crawfish, crawdads, freshwater lobsters, mountain
lobsters, mudbugs, or yabbies. Taxonomically, they are members of the super families Astacoidea and Parastacoidea. They breathe through feather-like gills. Some
species are found in brooks and streams where fresh water is running, while others
thrive in swamps, ditches, and paddy fields. Most crayfish cannot tolerate polluted
water, although some species such as Procambarus clarkii are hardier. Crayfish feed
on animals and plants, either living or decomposing, and detritus. The name “crayfish” comes from the old French word escrevisse. Some kinds of crayfish are known
locally as lobsters, crawdads, mudbugs, and yabbies. In the Eastern United States,
“crayfish” is more common in the north, while “crawdad” is heard more in central
and southwestern regions. In Australia (on the eastern seaboard), New Zealand and
South Africa, the term crayfish or cray generally refers to a saltwater spiny lobster,
of the genus Jasus that is indigenous to much of southern Oceania. In Singapore, the
term crayfish typically refers to Thenus orientalis, a seawater crustacean from the
slipper lobster family (Wikipedia 2019a).
Because of its important ecological role in freshwater ecosystems, crayfish have
been called a keystone species. The impact of these crustaceans on ecosystems is
more important than expected given their relative abundance or total biomass.
Because these species are both prey and predators, they have a central position in
the food chains of the ecosystem (Geiger et al. 2005).
Biology of Crayfish
Crayfish are found in freshwater environments such as lakes, dams, rivers, and irrigation canals ranging from sea level to sub-alpines. They can be found in most
substrate types. Larger populations are found in areas where there are shelters, and
low pollution, and no predators. Although crayfish are mainly a night animal, some
crayfish are observed during the day, especially in dark waters that provide little
protection from predators (Hollows 2016). Crayfish usually are seen in the darkness
of the evening and morning or at night. During the day they are hiding in pits or
2.3 Lobsters