Answer:
Bone marrow is the soft connective tissue of bone that includes red bone marrow and yellow bone marrow. Red bone marrow is <u>heteroglobic</u> (blood cell forming) and contains <u>redactive</u> connective tissue, immature blood cells, and fat.
In children, red bone marrow is located in the <u>cyclonic</u> bone of most of the bones in the body as well as the <u>antebellum</u> of long bones. Much of the red bone marrow degenerates and turns into yellow bone marrow as children mature into adults. As a result, adults have red bone marrow only in selected portions of the <u>irregular</u> skeleton. Some of these include the <u>dismantled</u> bones of the skull, the vertebrae, the ribs, the sternum, and the hip bones.
I think the answer is vibrssae or whiskers.
The concept of the struggle for existence<span> concerns the competition or battle for resources needed to live. It can refer to human society, or to organisms in nature. The concept is ancient, and the term </span>struggle for existence<span> was in use by the end of the 18th century. From the 17th century onwards the concept was associated with a population exceeding resources.
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STSN</span>
Answer:
At the base of Actinopterygii
*This is a unique characteristic of this group.
Explanation:
A peculiar characteristic organ observed in ray-finned fish (as well as in Sarcopterygii, or lobe-finned fish) but not in cartilaginous fish like shark is the swim bladder.
This organ is often described to be a sac containing gas. It helps these set of fish adjust its buoyancy and its position in the water by regulating the concentration of gas present in it.
The swim bladder is formed as a pouch coming off the embryonic digestive tract, and in chondrosteans and holosteans, with a set of teleosts e.g. the eels, it maintains an open pathway to the esophagus. In majority of the bony fish, the swim bladder is totally sealed off, as gas levels in their swim bladder are regulated by producing gas into the bladder via a network of capillaries, the rete mirabile (Latin word for "marvelous net").
The swim bladder is homologous to the lungs of tetrapods. Since they are formed in the same vein. Few fishes that have an open swim bladder employs it as a breathing organ.
