Six thousand reindeer once lived on a remote island in the Bering Sea
that was briefly their paradise. In what has become a classic story of
wildlife boom and bust, no reindeer live on St. Matthew Island now.
Three scientists just looked back at the St. Matthew's reindeer herd and
found that an extreme winter probably pushed the stressed animals to
their deaths.
The answer is "D"
The body's first line of defense is also known as Innate immunity and incudes mucous membranes. Both the intact skin and mucous membranes of the body offer a high degree of protection against pathogens.
A good example is the mucous membrane of the respiratory tract. It is lined up with cilia and covered with mucus. The coordinated beating of the cilia drives the mucus up to the nose and mouth where the trapped bacteria can be expelled.
(Lymph nodes and white blood cells belong to the second line of defense, not the first)
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.
Binary fission enables them to reproduce quickly.
Brown algae and dinoflagellates
Reason: Because they are the closest being in the same branch, makes them the most related.
Hope this helps! :))
