Question

Discuss adaptations for osmoregulation and buoyancy for aquatic fauna. Use examples to explain the different ways to address these challenges.

Answer 1

In Sea Water fishes: Osmoregulation

As for the intestine, it needs to cope with potential dehydration from the hyperosmotic seawater environment. Numerous Na+-K+-2Cl−-cotransporters (NKCCs) are located on the mucosal surface of the intestinal epithelia in Sea Water fish for absorption of these three ions in parallel with water absorption from the intestinal lumen. Water was hardly absorbed in the stomach and intestine, and water absorption predominantly took place in the rectum so that the wate can be expelled out effectively.

Sometimes, in Eels, it need to adjust saline pressure by nervous system. While neural mechanisms through drinking play an essential role in body fluid balance in marine teleost fish.

Hormones play an essential role in the regulation of ion and water balance in salinity transfer. In teleosts, one of the major hormones is the corticosteroid that facilitates the processes for the successful acclimation of fish from FW to SW. Cortisol is the major corticosteroid found in teleost fish, with release from inter renal gland being stimulated as fish are transferred from FW into SW. Thus it is also often referred to as a SW-adapting hormone.

Buoyancy adaptations:

Body shape - Thay have very slender body shape for swimming and to aid in burying in the mud for escape. They also have leaves like body for disguise.

Floatation - Thay accumulate gasses in some of their organs in heir bodies so they can easily float into the water.

Respiration - For respiration, they have gills, also they use simple diffusion. The shape and location of their respiratory organs also facilitate in providing buoyancy as they trap the atmospheric oxygen in the enlarged surface area of the respiratory organs like gills, hairs, skin to allow diving.

Locomotion - They evolved flattened legs for paddles, also they have additional hairs to increase the paddle effect.