Geotria
| Geotria | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Geotria australis , male |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name of the family | ||||||||||||
| Geotriidae | ||||||||||||
| Nelson , 1994 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Geotria | ||||||||||||
| Gray , 1851 |
Geotria is a species of lamprey that inhabits temperate and cold zones in the Earth's southern hemisphere. It has been found close to the coast in the southern Atlantic , the Indian Ocean , the southern Pacific and in rivers of southern Australia , Tasmania , New Zealand , Chile , Argentina , the Falkland Islands and South Georgia .
features
Geotria usually grows to 18 to 20 inches long. The greatest proven length is 62 cm. Like all lampreys, the species has an eel-like, elongated body. In sexually mature animals one can distinguish two clearly separated dorsal fins , while young animals have one continuous dorsal fin. The dorsal and caudal fins of not yet sexually mature animals are separated. In all other lamprey species, the dorsal and caudal fins have grown together.
The teeth of Geotria are spade-shaped, in all other lamprey species they are pointed or rounded. The oral disk has two large, centrally arranged teeth and two rows of teeth arranged on the side. Male Geotria develop a pronounced whitish throat pouch during the breeding season.
Geotria australis is at times a pentachromat , so it can perceive five different basic colors. Color vision changes over the course of life, likely depending on the environment.
Way of life
Geotria species live for the first four years as crossbones in the muddy bottom of rivers. After the metamorphosis into full-grown lamprey, the animals migrate downstream into the sea and live there as fish parasites for an unknown time. Geotria migrates up to 60 km up the rivers and streams to reproduce . The hike can take up to 16 months. During this time the animals do not eat. They hike when the sky is overcast, on rainy nights or during the new moon , usually at water temperatures of 12.0 to 14.5 ° C. To overcome obstacles, they also leave the water and meander across land for short stretches. After spawning, the animals die.
Systematics
The genus Geotria was introduced in 1851 by the British zoologist John Edward Gray in the first description of Geotria australis . For a long time it was monotypical with Geotria australis as the only species. In June 2020 Geotria macrostoma was revalidated, which means that Geotria consists of two species.
- Geotria australis , Indian Ocean , southern Pacific and in rivers of southern Australia , Tasmania , New Zealand and Chile
- Geotria macrostoma , southern Atlantic and in rivers of Argentina , the Falkland Islands and South Georgia
literature
- Joseph S. Nelson : Fishes of the World . John Wiley & Sons, 2006, ISBN 0-471-25031-7 .
- Wilfried Westheide & Reinhard Rieger : Special Zoology Part 2: Vertebrae and Skull Animals , 1st edition, Spectrum Akademischer Verlag Heidelberg • Berlin, 2004, ISBN 3-8274-0307-3
Individual evidence
- ↑ Functional characterization, tuning, and regulation of visual pigment gene expression in an anadromous lamprey , Wayne L. Davies, Jill A. Cowing, Livia S. Carvalho, Ian C. Potter, Ann EO Trezise, David M. Hunt and Shaun P. Collin 2007 in the FASEB Journal , accessed September 28, 2014
- ↑ Riva-Rossi, C., Barrasso, DA, Baker, C., Quiroga, AP, Baigún, C., Basso, NG (2020): Revalidation of the Argentinian pouched lamprey Geotria macrostoma (Burmeister, 1868) with molecular and morphological evidence. PLoS ONE, 15 (5): e0233792. doi: 10.1371 / journal.pone.0233792
Web links
- Geotria on Fishbase.org (English)