Aquatic and Marine Biology

• Benthic animals(benthos), refer to organisms who live at the lowest level(floor) of a water body(ocean or a lake or sea), sometimes even permanently attached to the bottom. For example, polychaete worms, bivalves, echinoderms, sea anemones, corals, sponges, sea squirts, turbellarians and larger crustaceans such as crabs, lobsters, etc.
• Hence Animals which live on the floor of the sea are called benthic is a true statement.
• So, the correct answer is 'True'.

The body of the fish is supported by endoskeleton made up of bones. Fish possess a streamlined body which helps them to swim in water. Fish swim with the help of their fins. Streamlined body helps in orientation of the fish movement in a particular path.

Starfish are known for their ability to regenerate amputated limbs and are characterized by flexible arms attached to a central disc. The central disc is essential for complete regeneration, however arms that are partially damaged/lost are regenerated by the organism

Starfish (echinoderms) possess remarkable regenerative abilities and can regenerate lost body parts, including whole arms or even a new body from a single severed arm under certain conditions.

Formation of new parts of the body, which are lost due to injury or accidents is called Restorative regeneration. Regeneration  of broken arms is called Restorative regeneration. It occurs in Echinoderms.

A. Fish - can regenerate almost any part of their central nervous system.

B.Amphibia – can regenerate their limbs.

C.Birds – regenerate their hair cells, feathers.

D.Sea cucumber - can regenerate entire alimentary canal.

So, the correct option is ‘ Sea cucumber’.

Many animals can regenerate, that is, regrow or grow new parts of their bodies to replace those that have been damaged. Echinoderms can regenerate missing limbs, arms, spines and even intestines (for example sea cucumbers). Some brittle stars and sea stars can reproduce asexually by breaking a ray or arm or by deliberately splitting the body in half. Each half then becomes a whole new animal. Planarians are flatworms when cut into pieces, each piece can grow into a new worm. Sea cucumbers have bodies that can grow to be three feet long and shows the phenomena of regeneration. Spiders can regrow missing legs or parts of legs. Sponges can be divided. The cells of the sponge will regrow and combine exactly as before. Starfish that lose arms can grow new ones, sometimes an entire animal can grow from a single lost arm. Birds (Aves) on the other hand, do not have this ability

Scientists have studied both octopuses and cuttlefish for their remarkable ability to change skin color and texture for camouflage, leading to biomimetic developments.

Frogs and earthworms are classic examples of organisms that utilize cutaneous respiration, meaning they breathe through their moist skin. While frogs also have lungs, their skin is a primary respiratory surface, and earthworms rely entirely on cutaneous respiration.

Mechanical energy is the sum of kinetic and potential energy. A swimming fish possesses both kinetic energy (due to motion) and potential energy (due to its position in the water column).

Cod, haddock and bass are all common examples of round fish. The majority of these fish species can be found in relatively shallow water; as a result they are regularly caught by sea anglers across the Europe.

During the last ice age the bank was part of a large landmass connecting Europe and the British Isles, now known as Doggerland. It has long been known by fishermen to be a productive fishing bank; it was named after the doggers, medieval Dutch fishing boats especially used for catching cod.

At the beginning of the 21st century, the area was identified as a potential site for the UK round 3 wind farm, being developed as Dogger Bank Wind Farm.

Chlorinated hydrocarbons like DDT pass into the food chain and increase in amount per unit weight of organisms with the rise in trophic level due to their accumulation in fat. Among the given animals, seagull which is a fish-eating bird and is present at a higher trophic level will have high levels of DDT deposition in its body.

Dichlorodiphenyltrichloroethane (DDT) is chemically an organochlorine that was used an insecticide. It is a stable compound that shows high solubility in the fatty tissues. When it is released in the water via the agricultural field surface run-off, it is ingested by the aquatic organisms like phytoplankton that are main producers in an aquatic food chain. From these, DDT continues rising up the food chain. Because successive consumers at the successive trophic level consume more food, it accumulates at the higher trophic level in greater amounts. This is called biomagnification. Sea/gulls and birds are the top consumers in an aquatic food chain, they will show the highest accumulation.

Blood platelets are found in mammals. Platelets, also called thrombocytes, are blood cells, whose function is to stop bleeding. Platelets have no nucleus: they are fragments of cytoplasm, which are derived from the megakaryocytes of the bone marrow, and then enter the circulation. These unactivated platelets are biconvex discoid structures.