Lepidophthirus macrorhini
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| Lepidophthirus macrorhini | ||||||||||
| Enderlein , 1904 |
Lepidophthirus macrorhini is a species of animal lice that specializes in living as a parasite on the southern elephant seal ( Mirounga leonina ). It is one of two species of the genus Lepidophthirus within the seal family Echinophthiriidae .
features
The males of Lepidophthirus macrorhini reach a body length of 2.5 to 3 millimeters, the females are about 2.25 millimeters long. They have a pale yellow- brown body color, the tibia and tarsi of the legs are dark brown and the claws and thorns are brown-black. The chest area has two dark brown spots on the top, separated by a paler line and flanked by lighter areas. The upper side of the abdomen is roof-tile-like and closely covered with chitin scales, which extend to the middle of the back and mix with thorns there. These thorns cover the entire body in varying lengths and form irregular and dense transverse rows. There are six to eight of these transverse rows per segment.
Lepidophthirus macrorhini has a broad head, which is densely covered with short thorns. At the back of the head, the animals have a wide appendage that pushes itself into the upper area of the chest area. The mouth opening on the underside is comparatively far forward and is surrounded by a bar that is open to the rear and four bristles. The antennae consist of four members, directly behind them there is a conspicuous bulge of the head with long thorns. The eyes are regressed and completely absent.
The legs are short and strong, with the front legs being slightly smaller than the following pairs of legs. The thigh ( femur ) is greatly shortened, the tibia and the one-unit tarsus merge directly into one another and are hardly separated from one another. In front of the tarsus there is a skeletal plate, a pretarsal sclerite , with strong and short teeth and on the tibia there is another process with similarly shaped teeth. The sternite of the first breast segment ( prothorax ) has a fork-like structure that is open to the rear.
The abdomen is not separated from the chest area and consists of nine segments, the first segment being reduced to the back plate ( tergite ). The segments 6 to 9 are strongly bent together. Spirits are located in the two posterior breast segments and in the second abdomen segment. In the females, the ninth abdomen segment has the elongated and narrow gonopods , which are fused in the front area and are long perched. The sex region is occupied by hair and thorns in the female, while the male has smaller scales here. The Aedeagus has only simple chitin clips as valves.
Way of life
Lepidophthirus macrorhini lives as an ectoparasite on the body of the southern elephant seal ( Mirounga leonina ), which is found in the Antarctic and spends most of its life in the sea. The louse must be adapted to both the extreme temperatures of the Antarctic and life in seawater. As an animal louse, Lepidophthirus macrorhini feeds on the blood of its host. To do this, the louse sticks its proboscis into the body of the elephant seal and pricks a capillary, the blood is then absorbed through the proboscis.
Adaptations to the habitat and way of life of the hosts
The lice on the body of the elephant seal are completely covered with salt water every time the seals dive and must be adapted accordingly for this way of life. They are exposed to extreme changes in temperature, the availability of oxygen, the presence of salt water and the amount of food. They have adapted to these changes through various strategies.
The elephant seals go ashore only once a year for four to five weeks, where the females give birth to their young and the mating of the animals takes place. Most of the adult seals are colonized by lice of the species Lepidophthirus macrorhini , the young animals are also infected in the short time after birth until they leave the colony.
The body of the elephant seal is covered by a short and hard, scale-like fur that is less dense in the area of the fins. Elephant seals are mammals and their body temperature is correspondingly higher than that of their surroundings. Thermal insulation takes place mainly through the thick layer of fat on the body, which is missing in the area of the fins. During studies on Macquarie Island , average air temperatures of 0 to 8 ° C were found. The skin temperature of the elephant seals is around 8 ° C and around 30 to 33 ° C, in the area of the fins around 24 to 34 ° C. At lower air temperatures, the skin temperature on the body drops, but it remains about the same in the area of the fins. In the sea, the temperature of the entire skin surface adapts to the water temperature.
The spread of lice on the body surface usually follows the areas of the body where excess heat is given off. They are found accordingly in the highest density in the area of the rear fins, where the highest temperatures arise. At the same time, the warming of the areas leads to a stronger blood flow in the capillaries there and the amount of food available for the lice increases.
Reproduction
The lice reproduce only on land. Here they reproduce very quickly and spread among the elephant seals and their young in the colony.
At temperatures of 25 to 35 ° C on the hosts, the females lay six to nine eggs per day, the nymphs hatch after five to ten days. They cannot hatch when the eggs are in the cold water; accordingly, the life cycle is tailored to the short phase of the shore elephant seal. In the time the young animals spend on land, the lice can develop two new generations.
Taxonomy and systematics
The first description of Lepidophthirus macrorhini was made by Günther Enderlein on the basis of several animals collected by Emil Werth during the German South Polar Expedition . He had collected them from a young male of the southern elephant seal on the Kerguelen in 1902 and brought them to Germany. Enderlein recognized it as a new species and described both the new genus Lepidophthirus and the new species. He found a closer relationship to the genus Echinophthirius , which parasitizes on the seal ( Phoca vitulina ) , but the differences established the description of a new genus .
Lepidophthirus macrorhini is today one of two described species of the genus Lepidophthirus within the family Echinophthiriidae, which specializes in life on seals . Very little information is available about the second species, Lepidophthirus piriformis , which lives on monk seals ( Monachus ).
supporting documents
- ↑ a b c d e G. Enderlein: Lepidophthirus n.gen., A louse of the elephant seal from Kerguelen Island. Zoologischer Anzeiger 23, 1904; Pp. 43-47. ( Full text at archive.org).
- ↑ a b c d e M.D. Murray: Insect parasites of marine birds and mammals. In: Lann Cheng: Marine Insects. Scripps Institution of Oceanography Technical Report, Scripps Institution of Oceanography, UC San Diego, 1976.
literature
- G. Enderlein: Lepidophthirus n.gen., A louse of the elephant seal from Kerguelen Island. Zoologischer Anzeiger 23, 1904; Pp. 43-47. ( Full text at archive.org)
- MD Murray: Insect parasites of marine birds and mammals. In: Lann Cheng: Marine Insects. Scripps Institution of Oceanography Technical Report, Scripps Institution of Oceanography, UC San Diego, 1976