Reproduction of sea lilies. Class of sea lilies (photo)

Unpredictable world of marine animals, it is full of surprises. Some of them, together with corals and algae form unique underwater gardens. Sea lilies are benthic animals, not plants, as it seems at first glance. They refer to the echinoderm.

Where do marine lilies live?

Their class has a fairly wide range of distribution. In the world's oceans, there are practically no places where sea lilies are not found. There are about 700 kinds of feather-stars. In Russian sea waters there are only 5 of their varieties.

Sea lilies have settled all the oceans. Depth for them is unimportant. They are everywhere equally good. And yet the bulk of these animals prefer to settle in warm ocean waters with thickets of coral reefs, located at shallow depths (up to 200 meters).

Types of sea lilies

The class of sea lilies is represented by two varieties of feather-stars - stalked and unstable. All individuals, regardless of their species, are attached to all kinds of objects under water. The stalked crinoids, having secured a stalk for anything, remain in this position forever. The zone of their vital activity is limited by the length of the stalk on which they swing.

Bezstebelachye lilies, having lost support, gained greater freedom of action. They, tearing themselves away from the substrate, are able to overcome insignificant distances. The animals swim at the expense of rays that work like fins. However, each stalk-deprived feather-star in the process of development does not pass the attached stalk stage. This feature and reproduction of sea lilies of both species brings them closer together.

Biological Description

The name of this class of animals has Greek roots. Crinoidea is translated as "like a lily." And indeed, the individuals belonging to this class, bizarre bodies, like a lush flower. The similarity with colors increases the colorful coloring of the body of feather-stars. Seen in the ocean, a beautiful creature, and I want to make his photo. Sea lilies - a delightful decoration of underwater gardens, the creation of which worked brilliant designer - nature itself.

Crinoids have a body in the shape of a cup with an oral cavity in the center. Up from the calyx, branching rays (arms) and corolla rise. In stalked crinoids, a peduncle is attached to the bottom of the calyx, growing to a length of up to one meter. The peduncle with supporting lateral appendages (cirri) is attached to the ground. The unsteady lilies have only moving cirrers, the ends of which are provided with either denticles or "claws". Thanks to them, unstable individuals cling to the ground.

The feather-stars became the only echinoderms, able to preserve the orientation of the body characteristic of their ancestors. The dorsal side is attached to the ground, and the surface that is provided with the oral cavity is turned upward. The basis of the structure of their bodies is a five-beam radial symmetry. The body is formed by five rays, capable of repeatedly decomposing and forming 10-200 "false hands". The rays are equipped with multiple lateral branches (pinnules).

Thanks to the blossoming corolla, an original network is formed that catches plankton and detritus. The rays that frame the inner side are provided with muco-ciliary grooves, which are reduced to the oral cavity. The food that gets into them goes to the mouth. The calyx on the edge of the conical eminence is equipped with an anal opening.

The formation of the outer skeleton is facilitated by calcareous segments. It is formed by two parts: an endoskeleton of rays and a stem. These bottom animals have ambulacral, nervous and sexual (causing the reproduction of sea lilies) system. The branching of all the designated systems penetrates into the cavity of the rays and the stem.

Crinoids from their brethren differ not only in orientation, characteristic for the dorsal-ventral axial line, which permeates the bodies of all individuals, but also by external configurations. The components of the ambulacral system in pen-stars are simplified. For example, it does not include ampoules designed to control the legs. Not found in individuals and madrepore plates.

Reproduction

Let's look at the multiplication of sea lilies. These echinoderms refer to dioecious animals. Sexual products fall into those pinnules that are located closer to the calyx. The male, as a rule, first sprinkles the sperm from the pinel, using special openings.

His behavior leads to stimulation of the female, which does not have any genital ducts. Its pins are simply torn, and eggs fall out of them. Fertilization of eggs is carried out directly in the water, after which they become barrel-shaped larvae of the dololarium. This is the reproduction of sea lilies.

Development of lobularia

After 2-3 days, the dolorolarium sits on the ground. Its front tip is strengthened on the substrate, any solid objects and even on itself similar individuals.

Having lost its cilia, it becomes immovable.

The stage of pentacrinus is expressed by the fact that a five-pointed structure is gradually manifested on the calyx. The stem grows, elongating, the rays develop, the attached disc increases. Doliolaria begins to resemble a tiny feather-star, swaying on the stem. Its size varies in a segment of 0.4-1 cm. Cold Arctic waters induce larvae to develop up to 5 cm in length. Over time, doliolaria elongates, differentiates into a stalk and calyx, where the oral cavity is subsequently formed . At this point, the cystoideal stage of development of the larva ends.

Differences in the development of groups

If the reproduction of sea lilies and the development of larvae are exactly the same, after the completion of the pentacrine stage in both groups of crinoids, further maturation flows differently. Stalked individuals, chained to one place, overgrow with new segments of the stem. Their lengthening stem looks like a stack of coins (after all, individual vertebrae are strung together).

The vertebrae have a movable joint that is provided by the muscles. The center of the stem is penetrated by a channel where nerves lie and other organs are hidden. Cirirs are located in two ways: either along the entire stem, or at its base.

The individual takes on an incredible similarity with the flower, which, in fact, demonstrates multiple posh photos. Sea lilies of the present have stems of different length, usually it is limited to 75-90 cm. And in fossil forms the length of the stems reached up to 21 meters. The feather-stars of antiquity were real giants.

The unstained lilies develop differently. After a month and a half, the calyx, independently breaking off from the stalk, starts free swimming. The peduncle dies with time.