Copepods – Philosophyllum (I)
Eukaryotic domain
animal kingdom
Subkingdom of eumetazoa
Ecdyanimal main phylum
Arthropod phylum
Subphylum Crustacea
General Outline of Polya
Copepods
Suborder Neosaurus
Naked naked general order
Philosopher water fleas
Calanoida is an order of arthropods in the order Calanoida that includes 46 families and about 1800 marine and freshwater species. In oceans around the world, copepods of the order Daphnia dominate plankton, accounting for 55–95% of all plankton samples. Thus the Hydroflea species occupy an important place in the food web of these habitats, harvesting energy from phytoplankton and algae and "repackaging" this energy to be "enjoyed" by predators at higher trophic levels.
1. Morphological characteristics
The body of this order is cylindrical and is clearly divided into a cephalothorax and abdomen. The cephalothorax is significantly broad, including the head (often healed with the 1st thoracic segment) and 4~5 thoracic segments. The 4th thoracic segment is closely connected to the 5th thoracic segment, and there is a movable joint between the 5th thoracic segment and the 1st abdominal segment. The posterior corner of the last thoracic segment sometimes extends laterally or posteriorly. The abdomen is narrow and male and female. The female abdominal part has 4 segments, and sometimes the 1st and 2nd abdominal segments heal each other, so there are only 2~3 segments. The male has 5 abdominal segments. The first abdominal segment of both sexes is a genital segment, but the female genital segment is larger, with genital protrusions on the ventral surface and 1 pair of genital foramen; Males have only 1 genital foramen, located on the left side of the genital segment. The first antennae are slender and also have male and female distinctions: the left and right antennae of females are symmetrical; The left or right antennae of males change to holding antennae in the family Hydrophnia. The second antennae are bibranched. The mouthparts consist of a large jaw, a 1st small jaw, a 2nd small jaw, and a jaw foot. There are 5 pairs of chest feet, and the 1~4th pair is double-branched, which is a swimming limb. The morphology of the fifth pair of pectoral feet in females is different from that of the first 4 pairs, and some are degenerate or completely absent; The fifth pair of pectoral feet in males is asymmetrical and often changes to a junction that places the clamped sperm pod on the female. Each tail fork usually has 5 tail bristles (sometimes reduced to 3~4); There is also 1 dorsal bristle in the inner terminal corner of the back of the tailfork. Often 2 eyespots, or none at all. Eggs are laid directly into the water or in 1 or 2 oocysts that attach to the ventral surface or sides of the genital segment.
2. Life habits
Most of the animals of this order live in plankton, and a few live benthic life. The feeding type is filter-feeding. Filter suspended particles of diatoms, bacteria, organic debris, etc. in the water.
3. Ecological distribution
(1) Distribution of water bodies
Oceans, lakes, reservoirs, ponds, rice field swamps, inland salt water, wells, springs, caves and other groundwater, and bryophytes. The number of copepods in rivers and other flowing waters is very poor; In still waters such as lakes and ponds, especially the eutrophic water body, the number of copepods is very abundant
Distribution of the philosopher's water flea - camp planktonic life, usually living in the open water zone of lakes, estuaries and pond weirs.
Distribution of water fleas - benthic life, they inhabit all kinds of waters other than open water zones, such as lakes, pond weirs, coastal zones of swamps, sediment in rivers, etc.
The distribution of sword water fleas - between the above two groups, the habitat is also diverse.
(2) Distribution leads to differences in size between individuals
Copepods in the same area are longer longer in winter than in summer, and individuals of the same copepod species in the north are sometimes larger than those in the south. For example, the average body length of Schmacreiaforbesi ♀ in Jianjiangkou in Guangdong is ~1.15mm in summer and ~1.19mm in winter; comparing specimens from Jiangsu and Xinjiang, the length of white sword water flea ♀ is 1.70-1.87mm in Xinjiang, while it is only 1.28mm in Jiangsu.
(3) Dormancy of larvae and adults
Many species of copepods can survive adverse environments, but copepod larvae (usually stages 1 to 5) and female and male adults are more common. Many species, such as the sword water fleas, begin to hibernate or hibernate at the turn of spring and summer or autumn, or spend the dry period of the waters in wet soil.
(4) The way larvae and adults hibernate
During summer or hibernation periods, their bodies are hidden in a cyst consisting of plant blocks with special secretions that stick to some mud blocks. Some sword water fleas mature ♀ with oocysts, and the oocysts in the cysts also survive adverse environmental conditions. There are also species that overwinter in the silt at the bottom of the water, such as the widespread sword water fleas.
4. Value
This order (e.g. Chinese water fleas) is the basic food for many economic fish and juveniles. Some species (such as Pegasus damphae) can be used as food for domestic animals and humans due to their large numbers, wide distribution and high nutritional value. In addition, some species can be used as indicators of ocean currents or water masses, and can also be used as experimental ecological, physiological and biochemical research objects.
5. Subordinate Family
Spindle Daphnia (Acartiidae)
Homocephalidae (Aetideidae)
Leucopodae (Augaptilidae)
Deep-horned water fleas (Bathypontiidae)
Family Calanidae
Cetoric water flea (Centropagidae)
Family Clausocalanidae
Dartwater flea family (Diaptomidae)
Eucalanidae
Heterorhabdidae
Lucicutiidae
Daizer Daphnia family (Megacalanidae)
Long-gased water flea family (Metridinidae)
Paracalanidae
Paraapontellidae
Horned water flea family (Pontellidae)
Pseudodiaptomidae
Pachy-shelled water flea family (Scolecitrichidae)
Subeucalanidae
Family Temoridae
6. Spindle water flea family
Acartiidae is a family of water fleas.
(1) Characteristics
Thin and small. The head has a single eye, the head is separated from the first thoracic segment, the fourth and fifth segments are healed, the abdomen has 3 segments for females and 4-5 segments for males. fifth pectoral female symmetrical, segments 2–3; Male single limb, asymmetrical, left 4, right 4-5 segments.
(2) Spindle water flea genus
Spindle Daphnia (scientific name: Acartia) is a genus of planktonic copepods in the family Spindle Daphnia.
Acartia southwelli is a genus of spindle water fleas in the family Acartia. It is distributed in Sri Lanka, India and Hainan, Guangdong, Tianjin and other places in China, mostly found in salt water or brackish water.
Females are 1.0 mm long. The cephalic segment is fused with the first thoracic segment, and the posterior horns of the cephalothorax are bluntly rounded. The abdominal part is 3 segments. The anterior side of the genital segment is slightly protruding on both sides. The tail fork length is greater than its width. The fifth thoracic foot is single-limbed. The second basal segment is oblong in shape with a long spiny bristle at the outer terminal corner. The basal half of the terminal segment is enlarged, the last half is sharp, and the two parts are inflected. Males are 0.87 mm long. The cephalic segment is distinct from the first thoracic segment, and the posterior horns of the cephalothorax are bluntly rounded. The ventral part is 5 segments. The length of the tail fork is approximately equal to its width. The left and right basal ganglia of the 5th thoracic foot heal. The right limb is long, with a horseshoe-shaped protrusion in the middle of the inner margin of segment 3; Section 4 is narrow and long, bent posteriorly, and folded in the shape of a humerus. The first segment of the left limb is oblong in shape with a pinnate bristle near the middle of the outer margin. The third segment is angular with a sharp spine at the end and a small spine along its medial side, and a lanceolate protrusion erected at the base of the inner margin of the segment, with a sharp spine at the apex.
(3) Heterohydrophnia
Acartiella is a genus of water fleas in the family Spindle Daphnia.
Acartiella sinensis is a species of spindle water flea in the genus Acartiella and is endemic to China. The additive word "sinensis" means "Chinese". Distributed in Guangdong, Fujian and other places, it belongs to the warm water species. Near the shore of the estuary semi-saline zone. It often inhabits and occurs in freshwater areas.
7. Family Hydroflea
Calanidae is a group of plankton belonging to the order Cephalidae. The body is cylindrical in shape and is clearly divided into a cephalothorax and abdomen.
(1) Characteristics
The cephalothorax of the family Hydrophnia is significantly wide, including the head (often healed with the first thoracic segment) and 4~5 thoracic segments. The 4th thoracic segment is closely connected to the 5th thoracic segment, and there is a movable joint between the 5th thoracic segment and the 1st abdominal segment. The posterior corner of the last thoracic segment sometimes extends laterally or posteriorly. The abdomen is narrow and male and female. The female abdominal part has 4 segments, and sometimes the 1st and 2nd abdominal segments heal each other, so there are only 2~3 segments. The male has 5 abdominal segments. The first abdominal segment of both sexes is a genital segment, but the female genital segment is larger, with genital protrusions on the ventral surface and 1 pair of genital foramen; Males have only 1 genital foramen, located on the left side of the genital segment. The first antennae are slender and also have male and female distinctions: the left and right antennae of females are symmetrical; The left or right antennae of males change to holding antennae in the family Hydrophnia. The second antennae are bibranched. The mouthparts consist of a large jaw, a 1st small jaw, a 2nd small jaw, and a jaw foot. There are 5 pairs of chest feet, and the 1~4th pair is double-branched, which is a swimming limb. The morphology of the fifth pair of pectoral feet in females is different from that of the first 4 pairs, and some are degenerate or completely absent; The fifth pair of pectoral feet in males is asymmetrical and often changes to a junction that places the clamped sperm pod on the female. Each tail fork usually has 5 tail bristles (sometimes reduced to 3~4); There is also 1 dorsal bristle in the inner terminal corner of the back of the tailfork. Often 2 eyespots, or none at all. Eggs are laid directly into the water or in 1 or 2 oocysts that attach to the ventral surface or sides of the genital segment.
(2) Life habits
The zoosyllides live a planktonic life , usually in the open water of lakes , estuaries , and pond weirs. The feeding type is filter-feeding. Filter suspended particles of diatoms, bacteria, organic debris, etc. in the water.
(3) Geographical distribution
The water fleas are warm temperate species, widely distributed in the Bohai, Huang and East China Seas, and are the dominant species in this water.
(4) Value
Détarian fleas (such as the Chinese water fleas) are essential food for many economic fish and juveniles. Some species (such as Pegasus damphae) can be used as food for domestic animals and humans due to their large numbers, wide distribution and high nutritional value. In addition, some species can be used as indicators of ocean currents or water masses, and can also be used as experimental ecological, physiological and biochemical research objects.
(5) Genus Hydrophea
Calanus is a genus of water fleas.
(1) Characteristics
The last two thoracic segments are separated, and the posterior corner of the terminal thoracic segment is bluntly rounded. The inner edge of the basal segment of the 5th thoracic foot is serrated , and the male has a larger left foot than the right foot. The genus is widely distributed and abundant, and is an important marine ticker and is the main food for many economic fish and baleen whales. Some species, such as Calanus fimarchicus, are very closely related to currents and water masses. Therefore, according to its distribution, it can explore the ins and outs of ocean currents and water masses, which has great reference value in production. Calanus sinicus, a water flea distributed in the China Sea. P5 serrations 17-22, males have short inner limbs on their left feet, reaching only or without reaching the end of the first segment of their outer limbs. It is a warm temperate species, widely distributed in the Bohai, Huang and East China Seas, which is the dominant species in this water. It is an important food for economic fish such as mackerel.
(2) Chinese water fleas
Calanus sinicus is a species of Arthropoda, Crustacea, Calanidae, and Calanus.
a. Morphological characteristics
The body of the Chinese water flea is long barrel, and the body length is only 2~3 mm. The most significant feature of this species is that the inner edge of the 5th thoracic foot and the 1st basal segment of the male and female has dentition (the number of teeth in females is generally 18~22, and in males it is generally 11~21). The bases of the teeth are connected to each other, the near central part of the dentition is significantly concave, and the tooth edges are small. The outer branch of the left foot of the male 5th pectoral foot is much longer than that of the right foot. The outer branches of the left foot are 1st and 2nd segments narrow and long, and the 3rd segment is short and tapered; However, the outer branch of the right foot is shorter, and the end of segment 3 does not reach the center of segment 2 of the outer branch of the left foot. The end of segment 3 of the inner branch of the left foot generally does not exceed the end of segment 1 of the outer branch.
b. Life habits
The Chinese water flea is a small marine zooplankton. The feeding type is filter-feeding. Filter suspended particles of diatoms, bacteria, organic debris, etc. in the water.
c. Reproduction
The breeding period of Chinese water flea in the coast of China is generally 3 times, the period varies with the sea area, in the East China Sea Fujian coast: December ~ January, February ~ March, end of April ~ May.
d. Distribution
It is mainly distributed in the coastal areas of the Yellow Sea and East China Sea in China, and its large number is the dominant species in these waters.
e. Economic Value
The Chinese water flea is the main feeding object of many economic fish and is of great significance in fishery production.
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