Generally, an external fixator is mounted quite securely to the bone, and can withstand mild contact, any positioning of the body, and oftentimes even weightbearing immediately after surgery. In fact, it is often more comfortable to pick up the leg by grabbing the fixator, rather than holding the leg itself.he fixator is composed or one or more metal bars and rings, which in turn connect to a child via metal pins and wires. By gradually manipulating the fixator on the outside, we can carefully control the position of the bones and joints on the inside.
Habitat and Distribution. Pin this Image. Green sea urchins used to live in cold waters of the sub Polar Regions. They live in Northern cooler part of the Pacific and Atlantic Ocean. Some also live in the Arctic too. The sea animal can be found in rocky sea beds. They often live in the low depth tidal zones.
The mouth of the sea urchin (known as the Aristotle's lantern), is found in the middle on the underside of the sea urchin's body and has five tooth-like plates for feeding. The anus of the sea urchin is located on the top of the body.As with other echinoderms, sea urchins do not have a brain and instead rely on their water-vascular system which is like a circulatory system and comprises of water-filled channels that run through the body of the sea urchin.he spines of the sea urchin are used for protection, to move about, and to trap food particles that are floating around in the water. Sea urchins have five paired rows of tiny tube feet which are found amongst the spines.