Map cone

Map cone snail
	Conus geographus
Systematics
Partial order :	New snails (Neogastropoda)
Superfamily :	Conoidea
Family :	Cone snails (Conidae)
Genre :	Conus
Subgenus :	Gastridium
Type :	Map cone snail
Scientific name
	Conus geographus
	Linnaeus , 1758

The map cone or geographic cone , also the map cone snail ( Conus geographus ), is a snail from the family of cone snails (genus Conus ). The venom of this fish-eating cone snail, which is widespread in the Indo-Pacific , is considered to be one of the most dangerous in the animal kingdom.

features

Conus geographus has a wide, thin-walled, often convex snail shell , which is approximately cylindrical in its middle and rear section and which reaches 6.5 to 16.6 cm in length in adult snails. The basic color of the housing is white with a bluish-gray, purple or pink hue. The surface around the body is almost smooth and has a fine, frequently interrupted pattern of brownish to reddish brown lines and small tent-shaped spots, which are often arranged in two irregular bands. The protoconch is pink to red, the mouth white. The flattened thread is grooved and has knots. The periostracum is gray to yellowish or reddish brown, thin and can be translucent. The convex-cylindrical shape of the housing with a wide middle section and the strongly flattened thread set the map cone apart from other types of conus.

View of the estuary
Rear view
View on thread

The animal has a broad, massive foot, the white, brown spotted and striped upper side of which is covered by a pale orange, white dotted stripe. The rostrum is yellow-brown, dorsally with a dark brown marbling and notched at the distal end. The antennae are white with a light brown tip, the sipho white with dark brown horizontal stripes on light brown spots and a white tip. The sole of the foot is white with light brown spots. The hues of the animal vary.

The radula teeth connected to a poison gland have a barb at the tip and a cutting edge with a small barb opposite. They are sawed back to the middle of the tooth with about 125 teeth. At the base of the tooth there is only a weak nodule and no spur.

distribution

The map cone is widespread and occurs in the Red Sea and the Indian Ocean around Chagos , Madagascar , Mauritius , Mozambique and Tanzania , as well as in the Indo-Pacific with the exception of Hawaii.

habitat

Map cones live in the intertidal zone of coral reefs up to 20 m deep, where they prefer sandy seabed.

Life cycle

Like all cone snails, Conus geographus is separate sexes and the male mates with the female with his penis . Veliger larvae hatch from the egg capsules , which in turn undergo a metamorphosis into snails. Approximately 54 capsules are released per spawn, each containing 14,500 to 17,800 eggs. The eggs are about 190 µm in diameter. From this it is concluded that the pelagic period of the Veliger lasts about 24 days.

nutrition

The prey of Conus geographus consists mainly of fish , molluscs are also eaten. In this species, the fish are swallowed without being stung beforehand, but they can be killed in the foregut by a poisonous tooth. The nocturnal map cone crawls up to fish that are resting, releases insulin into the water and puts its "wrong mouth" over them. The insulin apparently causes the fish to suffer a hypoglycemic shock and is thus immobilized. In this way, several small fish can be captured at once, which are then stung one after the other in the mouth with the poisonous radula teeth . In contrast to "harpooning" species such as the striped cone snail , the map cone is ready to eat more fish in its rostrum, even with predigested fish. It is one of the largest cone snails and has a particularly thin shell, which makes it extremely agile. Cone snails 8 to 9 cm long can prey on fish 13 to 14 cm long. Fish killed recently are also eaten.

Importance to humans

Conus geographus is a popular collector's item due to its patterned housing, so that humans can be considered a main enemy. However, it is not included in the red list.

Like other cone snails, the map cone uses its poisonous harpoon not only to catch prey, but also for defense. Its fang can penetrate gloves and diving suits. The poison from the map cone is one of the most dangerous for humans and has caused more than 30 deaths. The poison consists of several hundred different toxins. There is no antidote , so treatment is aimed at keeping the person alive until the toxins are gone.

Some toxins ( conotoxins ) from Conus geographus have a strong analgesic effect and are therefore being investigated for medical applicability. A toxin obtained from Conus geographus is Contulakin-G (Conantokin).

literature

George Washington Tryon: Manual of Conchology, structural and systematic, with illustrations of the species , vol. VI; Academy of Natural Sciences, Philadelphia 1884. C [onus] geographus Linn., P. 88.
Jerry G. Walls: Cone Shells: A Synopsis of the Living Conidae TFH Publications, Neptune (New Jersey) 1979. p. 506.
Dieter Röckel, Werner Korn, Alan J. Kohn: Manual of the Living Conidae Vol. 1: Indo-Pacific Region . Verlag Christa Hemmen, Wiesbaden 1995. The texts on the individual cone snail species of the Indo-Pacific are published on The Conus Biodiversity website with the permission of the authors (see web links).