The stem is composed of many annular bone plates, and there are often appendages called root rolling branches or rolling branches. The fixed end of the stem is unfolded into a disc shape, and some of them are finger-shaped, leaf-shaped or anchor-shaped, so as to be fixed on the seabed. The rolled branches of Haiyang teeth are concentrated around the middle backboard for crawling or temporary fixation on the seabed. The number, number and shape of branches are important basis for the classification of marine teeth.
The crown includes calyx and wrist. At the beginning, the calyx consists of two circles of bone plates, with five plates in each circle. The next circle of 1 is called the bottom plate, and the last circle of 1 is called the mouth plate. After that, the mouth plate becomes petal-shaped. There are five wrist spokes supported by the 1 ring between the two ring plates. A calyx with this structure is called a single ring calyx. If 1 subring substrate differentiates again under the substrate, it is called bicyclic calyx. Most living sea lilies are single-ring calyx. The calyx of Ophiopogon japonicus is undeveloped and disc-shaped, and only the middle back plate and the radial plate can be seen. The mouth and anus face upwards, and the groove is connected with the mouth. The ditch is partly open to the wrist, and the side of the ditch is covered with cilia, which can transport food into the entrance, so the ditch is also called the food ditch.
The number of wrists was originally five, and they often branched into multiple ones. So there are/kloc-0 times (original wrist disc), the second time (double row disc) and the third time (palm disc). The wrist plate corresponding to the bifurcation point is called bifurcation axis. The number of wrist plates from 1 bifurcation axis to 1 bifurcation axis often varies with species. When describing sea lilies, symbols are often used to indicate the number of wrist plates and the position of immobile joints. For example, Ⅱ BR4 (3+4) indicates that there are four carpal bones for the second time, and there is an immobile joint between the third and fourth bones.
There are a series of feather branches on both sides of the wrist, which appear alternately on one side of each wrist joint. So every joint has a 1 feather except the lower 1 joint of the immobile joint. Feather branches are composed of feather nodes, and the number and shape of feather nodes are very important in classification. When describing, P, P, … stands for 1, 2, 3 feathers are outside the unbranched wrist, and P, P, … stands for 1, 2, 3 feathers are included … (Figure 2). P, p, p are used to represent the first 1 wrist, the second wrist and the third wrist.
The gonad is located in the reproductive feather branch, and the mature germ cells break the wall of the feather branch and put it into the water, or keep it attached to the feather branch. The embryo has cilia, and the unique cilia ring of Liliaceae is obtained after breaking the egg membrane. The larvae of sea lilies are barrel-shaped, so they are called bottle-shaped larvae. The bottle-shaped larvae further developed into sessile larvae.