Sea urchin shell, or 'test'. Each white band is the location of a row of tube feet; each pair of white bands is called an ambulacrum There are five such ambulacra; the penta-radial symmetry reveals a kinship with sea stars. In zoology, an ambulacrum is an elongated area of the shell of an echinoderm in which a row of tube feet are arranged.

2017年6月13日 · The ambulacra are petal-shaped and hence called petaloids and are equipped with respiratory podia. The ambulacra continue over the ambitus to the peristome. Irregular urchins lack gills. Irregular echinoids are divided into …

Unlike regular echinoids where the ambulacra run from the apex of the test to the mouth, irregular echinoids have developed a flower like structure, called the petaloid ambulacra, populated by many small pore pairs for tube feet on the aboral surface of the test.

... test is composed of five ambulacral zones (Figure 2a) in which the plates have rows of pores arranged in pairs (for the 'hydraulic fluid' which maneuvers the tube-feet) and tubercles (knobs...

2023年6月30日 · Echinoids, or sea urchins, have a robust, internal skeleton (the test) composed of numerous, fixed, calcite plates. Instead of arms the test has five narrow zones formed from perforated plates (the ambulacra) through which the tube feet emerge. These porous segments alternate with broader areas (the inter-ambulacra) that lack pores.

Each ambulacrum of sea urchins, like that of the majority of other echinoo derms, has a skeleton, which reflects the growth of radial ambulacral canals. The skeleton distinctly shows multiple ...

An ambulacrum is composed of two rows of tube feet; one is indicated by the double arrow from publication: Influence of body size on tube feet morphology and attachment capacity in the sea...

All sea urchins have ambulacra, but not all sea urchins have petaloids . Petaloids are specialized ambulacra, found only on the aboral side of the animal, found only in the Irregularia . They are called petaloids for their flower petal-like shape. In these specimens here, (this is

Echinoids (sea urchins) are vagrant, benthic, non-stalked (eleutherozoan) echinoderms with no free arms: the ambulacra are confined to the body (which is typically globose or discoidal in form). The ossicles of an echinoid skeleton are firmly fused together, making the test rigid.

Amphidotus cordatus or Echinocardium cordatum, commonly called a sea urchin, viewed from above. a, anterior ambulacrum, forming with b, b, anterolateral ambulacra, the trivium; c, c, two posterolateral ambulacra, forming the bivium; d, madreporic tubercle surrounded by genital pores; e, intrapetalous semita or fasciole; f, circumanal semita ...