Variety of species of marine animals so widespread that humanity will not soon be able to study them in their entirety.However, even a long time and well-known outdoor aquatics can surprise hitherto unseen features.For example, it was found that the most common hydroid (jellyfish) will never die of old age.It seems that this is the only known creature on earth possesses immortality.
General morphology
hydroid jellyfish of the type coelenterates, hydroids class.These are the closest relatives of polyps, but arranged them harder.Probably everyone is well aware of how to look like a jellyfish - translucent discs, umbrellas or bells.They may have a ring-shaped constriction in the middle of the body or even be in the form of a ball.Medusa has no mouth, but there are oral proboscis.Some individuals have even small pinkish tentacles at the edges.
digestive system of jellyfish is called gastrovascular.They have the stomach, from which the periphery of the body depart four radial channel, flowing into a common annular channel.
tentacles with stinging cells also are located on the edges of the umbrella body, they serve as both organ of touch, and a tool for hunting.The skeleton is missing, but there are muscles that make jellyfish moves.Some subspecies of the tentacles, and transformed into statoliths statocysts - organs of equilibrium.The method depends on the type of movement to which it belongs concrete hydroid (jellyfish).Reproduction and their structure will be different, too.
hydromedusae The nervous system is a network of cells that form at the edge of the umbrella and two rings: external charge sensitivity, internal - for the movement.Some have light-sensitive eyes, arranged on the basis of the tentacles.
types hydroid jellyfish
subclasses having the very organs of equilibrium - statocysts called trahilidami.They move through the expulsion of water from an umbrella.They also have a sail - a ring-shaped growths on the inner side, tapering out of the body cavity.He adds jellyfish speed when driving.
Leptolidy statocyst deprived, or they are transformed into a special bubble, within which there may be one or more statoliths.They move in the water is not as reactive, as their umbrella can be reduced and often intense.There are also
medusoid hydrocorals, but they are underdeveloped and little resemblance to ordinary jellyfish.
chondrophores live in large colonies.Some of them vypochkovyvaet jellyfish polyps that continue to live independently.
siphonophores - hydroid (jellyfish), whose structure is unusual and interesting.It's a whole colony, in which each performs its role in the functioning of the whole organism.Outwardly, it looks like this: on top of a large bubble in the form of a floating boat.He has glands that produce gas, helping to float to the top.If siphonophores want to go back deep into - it just relaxes your muscular body closer.Under the bladder located on the trunk of the other in the form of small jellyfish swimming bells, followed gastrozoidy (and hunters), then gonofory whose purpose - procreation.
Reproduction
Medusa hydroid is male or female.Fertilization usually occurs outside, rather than inside the body of the female.Gonads jellyfish are located either in the ectoderm of the mouth of the proboscis or the ectoderm under the umbrella radial channels.
Mature germ cells are outside of the formation of special breaks.Then they begin to break up, forming a blastula, some cells which then retracts inside.The result is the endoderm.In the process of further development of a certain number of its cells degenerate to form a cavity.It is at this stage of the fertilized egg becomes a larva-planuly, then settles to the bottom, where it is converted into gidropolip.Interestingly, he begins to bud new polyps and small meduzok.Then they are growing and developing as independent organisms.In some species of planul formed only medusae.
variation fertilization depends on what type, species or subspecies belongs hydroid (jellyfish).Physiology and reproduction, as well as the structure vary.
where they live
vast majority of species live in the sea, they are much less common in freshwater.You can meet them in Europe, America, Africa, Asia and Australia.They may appear in greenhouse tanks and artificial reservoirs.Where do the polyps and hydroids as a subject in the world, until the science is unclear.
siphonophores chondrophores, hydrocorals, trahilidy live exclusively in the sea.Only leptolid can be found in fresh water.But representatives and dangerous among them is much less than in the sea.
Each species of jellyfish takes its habitat, for example, any particular sea, lake or bay.To expand it can only due to the movement of water, especially the jellyfish do not capture new territories.Some are more like the cold, while others - heat.They may be closer to the surface or a depth.The latter is not peculiar to migration, and the first do so in order to find food, leaving day deeper into the water, and at night again rising to the top.
Lifestyle
first generation in the life cycle hydroid - a polyp.Second - hydroid jellyfish with a transparent body.Such is its strong development does mesogloea.It is gelatinous and contains water.It is because it is difficult to see the jellyfish in the water.Hydroids due to variability of reproduction and the presence of different generations can actively spread in the environment.
Jellyfish consume zooplankton food.The larvae of some species feed on fish eggs and fry.But at the same time they themselves are part of the food chain.
hydroids (jellyfish), a way of life, in fact, devoted to food, usually very rapidly, but, of course, does not reach such proportions as stsifoidy.Typically, the diameter of the umbrella hydroid does not exceed 30 cm. Basic their competitors - planktivorous fish.
course they predators, and are quite dangerous to humans.All jellyfish have stinging cells, which are used during the hunt.
How are hydroids from stsifoidov
The morphological features is the presence of the sail.Stsifoidy do not.They are usually much larger and live exclusively in the seas and oceans.Arctic tsianeya in diameter up to 2 m, but the poison of its stinging cells barely able to cause major harm to the person.Grow to large sizes stsifoidam helps more than hydroids, the number of radial channels gastrovascular.Some types of such a jellyfish used as human food.
difference exists in the type of motion - hydroids cut groove as at the base of the umbrella and stsifoidy - all the bell.At last longer tentacles and sensory organs.Their structure is also different, since there stsifoidov muscle and nerve tissue.They are always dioecious, they have vegetative reproduction and colonies.It singles.
scyphomedusae are amazingly beautiful - they may be of different colors, have fringes on the edges and the bizarre shape of a bell.These are the waters of the inmates are the heroines of TV programs about the sea and ocean animals.
hydroid jellyfish immortal
Not so long ago, scientists discovered that the cnidarian jellyfish turitopsis nutrikula have an amazing ability to rejuvenate.This type never dies a natural death!It can be any number of times to run the regeneration mechanism.It would seem that everything is very simple - reaching old age, jellyfish turns back into a polyp and has passed all stages of growing up again.And so the circle.
Nutrikula lives in the Caribbean and has a very small size - the diameter of its umbrella just 5 mm.
That hydroid jellyfish immortal, it became known by accident.The scientist Fernando Boero in Italy studied hydroids and conducted experiments with them.Several individuals turitopsis nutrikula were placed in an aquarium, but the experience for some reason was delayed for such a long period, the water dried up.Boero to find it, he decided to explore the remains of dried and realized that they did not die, but simply threw tentacles and become larvae.Thus, jellyfish adapted to adverse environmental conditions and zakuklilals in anticipation of better times.After placing the larvae into the water they turned into polyps, the life cycle has started.
Hazardous representatives hydroid jellyfish
most beautiful view of a ship called the Portuguese (siphonophores Physalia) and is one of the most dangerous sea creatures.Its bell shimmers in different colors, as if alluring to her, but to approach it is not recommended.Physalia can be found on the coast of Australia, the Indian and Pacific Oceans, and even in the Mediterranean.Perhaps this is one of the biggest species of hydroids - the length of the bubble can be 15-20 cm. But the worst - it's tentacles, which can go to a depth of 30 m. Physalia attack their prey with poisonous stinging cells that leave severe burns.It is especially dangerous to meet a ship with the Portuguese people who have weakened immune system, prone to allergic reactions.
In general hydroid jellyfish are harmless, unlike their sisters stsifoidov.But generally it is better to avoid contact with any representative of the species.They all possess stinging cells.For some, their poison will not turn back problem and someone will harm more serious.All depends on the individual.
