Short-snouted seahorse
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Short-snouted seahorse ( Hippocampus hippocampus ) on Ascophyllum nodosum |
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| ( Linnaeus , 1758) |
The short-snouted seahorse ( Hippocampus hippocampus ) is a type of bony fish ( ray- finned fish ) from the genus of seahorses , which is common in seagrass meadows in the northeastern Atlantic Ocean and the Mediterranean .
features
The short-snouted seahorse is up to 15 cm long. It has a protruding thorn above each eye. The slightly upwardly curved snout of Hippocampus hippocampus is less than a third of the length of the head for the proportions of a seahorse. The dorsal fin used for propulsion has 16 to 18 rays with a dark stripe parallel to the edge. The 13- to 15-rayed pectoral fins start below the gill openings and serve in particular for stabilization and control. Ventral fins are missing as well as a caudal fin. The bone plates with their nodules give the seahorse its curved and at the same time nodular shape. The animal's body surface is black, pink, orange, or brown, and sometimes pale mottled. The tapering, curled prehensile tail is used to attach it to plants and cannot be actively bent backwards.
distribution and habitat
Hippocampus hippocampus is widespread in the northeastern Atlantic Ocean from the North Sea and the northern coast of Scotland to the Canary Islands , Azores , Madeira and Senegal, as well as in the Mediterranean , where it is particularly common on the coasts of Italy . In the German Bight it was considered to be extinct due to the destruction of the seagrass meadows by fungal infections since the 1930s, but in 2003 and 2008 two and three seahorses respectively were found as bycatch by fishermen off the Schleswig-Holstein and Lower Saxony coasts, which in turn is interpreted as a sign of a return of the seagrass meadows. In 2007 seahorse colonies were found in the Thames near London and Southend-on-Sea .
The seahorse prefers to live in shallow sea water in seagrass meadows on muddy ground as well as in river mouths ( estuaries ), where it has been found at sea depths of up to 77 m. The dense plants offer it a good camouflage. As a very slow swimmer, it has a limited range and is mainly transported by strong currents in storms clinging to torn plants.
Reproduction
In short-snouted seahorses, both males and females reach sexual maturity in the first mating season after their birth, which depends on temperature, water and water current. The sexually mature male can be recognized by his belly pouch, which is used to hatch the eggs.
The short-snouted seahorse usually lives in a monogamous couple relationship in which males and females regularly greet each other for a few minutes. The males have a territory they against male peers defend in which the enemy is attacked with his nose or wrestle two males with intertwined tails. The inferior flattens out and becomes darker.
When the male is ready to mate, it pumps water into and out of the belly pocket. The female directs her head towards the surface of the water, showing that she is ready to mate. She now orientates her genital opening towards the male's belly pouch and lays her pear-shaped eggs into it, where they are fertilized by the male's sperm. After about 6 to 10 seconds the eggs are transferred and the male's belly pouch closes.
The fertilized eggs are surrounded by a tissue in the abdominal pouch, through which the embryos are supplied with oxygen and nutrient-rich blood via capillaries and which thus takes on the function of a placenta . In addition, the embryos are also supplied by the yolk of the eggs from the female . During this time, the male produces the hormone prolactin , which triggers the dissolution of the outermost layer of the eggs, creating a nutrient-rich placenta fluid. 20 to 21 days after the transfer and fertilization of the eggs, the male gives birth to the young, the number of which is around 50 to 100, depending on the age of the male, with older males giving birth to more children. The fry are left to their own devices immediately after birth. The male can mate with the female again just a few hours later in order to allow more young to grow in his belly pouch. In the meantime, new eggs have matured in the female.
nutrition
The short-snouted seahorse feeds on small crustaceans , preferably small shrimps , amphipods and copepods , for which it waits in wait. When prey swims by, it sticks out its head and sucks it in through its toothless snout. The seahorse only has a simple intestinal canal with no stomach-like enlargement, so the prey quickly passes through the intestines. The average adult seahorse eats around 30 to 50 small shrimp a day to keep its fill.
literature
- Rudie H. Kuiter: Seahorses: pipefish, shredded fish and their relatives , Ulmer (Eugen), 2001, ISBN 3-80013-244-3
Web links
- M. Sabatini, S. Ballerstedt: Short snouted seahorse (Hippocampus hippocampus). In: H. Tyler-Walters, K. Hiscock (Eds.): Marine Life Information Network, Biology and Sensitivity Key Information Reviews. Marine Biological Association of the United Kingdom, Plymouth 2007.
- Short snouted seahorse. Joint Nature Conservation Committee, April 30, 2018.
- Short-snouted seahorse on Fishbase.org (English)
- Hippocampus hippocampus in the Red List of Endangered Species of the IUCN 2013.1. Posted by: Project Seahorse, 2017. Retrieved August 14, 2018.
Individual evidence
- ^ Lena Ullrich: North Sea: seahorses surfaced. Geo online, undated, accessed August 14, 2018.
- ↑ North Sea - seahorses return. Focus (jsc), August 21, 2008.
- ↑ Rare seahorses breeding in Thames. BBC News , April 7, 2007.