Chambered nautilus
Nautilus pompilius, Blue Reef Aquarium, Southsea, UK
The Common Nautilus, also ship boat (Nautilus pompilius ) is a cephalopod of the family of nautilus, which is common in the Pacific Ocean. It is the most widespread species of this family.
Features
The case of Nautilus pompilius is thin-walled and can reach a diameter of 30 cm. The smooth surface has a white base color, on which - alternating brown and white bands - as with other nautilus species. The navel of the case is similar to Nautilus belauensis closed by a callus.
The interior of the winding as a logarithmic spiral shell, which cuttlebone, consists of up to 30, and sometimes even more than 38 gas-filled chambers, which by means of intermediate walls ( septa ) are separated from each other. When newly hatched animal there are only four chambers. The animal lives in the outermost, youngest chamber, the body chamber are formed from which further by formation of new septa chambers of Phragmokons. The gas mixture containing about 0.30 bar nitrogen, 0.29 bar oxygen and 0.0005 bar argon, passes through an extension of the animal, the Siphunculus ( Sipho ), in the still partially filled with water wells. The Siphunculus is traversed by blood vessels, can be released and absorbed through the gases, and as the buoyancy of the animal will be adjusted in the water. The shell can withstand a pressure of about 60 bar, which corresponds to 600 meters water depth.
The animal can withdraw into the shell and close them by a powerful hood -like hood.
The up to 90 tentacles are coated with a sticky secretion, to retain prey.
The horny beak, whose lower half is stronger than the upper, has calcified tips. The radula in each row is 13 pieces with Rachiszähnen, two side teeth, two marginal teeth and two marginal plates.
Like other nautilus Nautilus has pompilius hole eyes.
The Nautilus, which can float in the water with the help of his gas-filled Phragmokons moves away slowly rocking, and it is not faster than two inches per second.
Reproductive cycle
The male is looking to the female with the help of smell. When copulation four modified tentacles of the male copulatory organ serve as, with the help of which the spermatophores, wrapped in jelly sperm are transferred to the female. In the oviduct, the jelly dissolves, and the sperm fertilize the egg. The very yolk-rich eggs are deposited in shallower water. Only after about 12 months hatch already 3 cm long juveniles. Nautilus pompilius can be about 20 years old, so live significantly longer than octopuses and squids.
Dissemination
The Common Nautilus lives in tropical waters of the western Pacific and the eastern Indian Ocean. It prefers the slopes of coral reefs, where it occurs at depths of about 400 meters to 650 meters, at night and up to 100 meters water depth.
The subspecies Nautilus pompilius pompilius reached the enclosure sizes of about 30 cm, lives by the Andaman Sea to Indonesia to Fiji and from southern Japan to the Great Barrier Reef of Australia. The other subspecies Nautilus pompilius suluensis that is only up to 16 cm tall, is limited to the Sulu Sea in the southwestern Philippines.
Way of life
Nautilus pompilius is nocturnal and feeds on small crabs, besides also on carrion and occasionally small fish.
Use and threats
Nautiluses be fished like other cephalopods for their meat. The shell of Nautilus pompilius is also collected as souvenirs and collectors item. Although it is by far the most common Nautilus - type, it is therefore also at risk. Due to the slow rate of propagation losses are difficult to balance.
System
The name Nautilus pompilius goes back to the Systema Naturae of Carl Linnaeus, the Greek genus name ναυτίλος " seaman " means. Nautilus pompilius is one of five extant species of the genus Nautilus or seven kinds of Nautilidae family. There are two subspecies, Nautilus and Nautilus pompilius pompilius pompilius suluensis.