The muscle fibers within muscle cells are divided into myofibrils, which are further divided into , the contractile units of muscles.

the answer is sarcomeres

Nesting & Foraging behavior

Explanation:

Seabirds are generally tertiary consumers and / or marine predators that, in marine foodwebs, occupy the upper trophic level. They are very well adapted to all marine ecosystems and feed on a variety of prey: from micro-crustaceans to fish and cephalopods.

Generally, seabirds are observed performing a nesting behavior, by laying eggs near the shore, and then are found exhibiting foraging behavior -searching and foraging for prey- in both the coastline and pelagic zone, also known as the open sea.

Seabirds exhibit different foraging behaviors, for example, the surface feeding behavior which involves flying along the surface with their beak  in the water. Gulls, albatrosses and petrels are examples of surface feeders.

On the other hand, plunge diving involves preying on fast marine organisms by diving into the water during their flight. Pelicans are example of seabirds who engage in this behavior.