Aquatic and Marine Biology

Seahorses are fish (class Actinopterygii), family Syngnathidae. They have gills, swim bladder, and fins like fish. The male carries eggs in a pouch. Insects are arthropods, echinoderms include starfish, mammals have hair and mammary glands.

Octopuses stay deeper in the ocean. They have 8 arms and catch the prey that moves towards them. They have gills to help them breathe in water. They do not have streamlined body.

Incomplete divided ventricles can be seen in the heart of crocodiles.

Flyingfish or exocoetus is a fish.

Scoliodon has a cartilaginous endoskeleton.

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An elver is the specific term for a young eel that has developed from the larval stage (leptocephalus) but is not yet fully mature. They migrate from the ocean back into freshwater rivers where they grow into adult eels.

In marine teleost fishes, trimethylamine oxide occurs as a waste product in large quantities.

Aquaculture is the farming of aquatic organisms like fish in controlled environments. It creates artificial marine conditions for healthy fish development.

Salmonella is a genus of rod-shaped gram-negative bacteria that causes one of the most common foodborne illnesses worldwide. It typically spreads through contaminated food products like eggs, poultry, meat, and unpasteurized milk. Symptoms include diarrhea, fever, and abdominal cramps, usually appearing 6-72 hours after infection.

Organisms survive at the bottom of frozen lakes because water at the bottom remains liquid due to water's unique density properties. Water is densest at 4°C, so the coldest water sinks and freezes at the surface, creating an insulating ice layer while warmer water (around 4°C) stays at the bottom, allowing aquatic life to survive.

The shark possesses neither lungs nor swim bladders, using other methods for buoyancy and respiration. 'Neither' correctly pairs with 'nor' in a negative construction, and 'possesses' is the correct singular verb form.

Catla catla (catla), Labeo rohita (rohu), and Cirrhina mrigala (mrigal) are collectively known as Indian major carps and are all freshwater fish widely cultivated in aquaculture for food. All three are important edible fish species in South Asia.

Herring is the dominant pelagic fish in the North Sea ecosystem. The North Sea herring fishery has been commercially crucial for centuries, supporting the UK's fishing industry. Cod, halibut, and mackerel are also present, but herring biomass has historically been highest. Pelagic fish live in the water column (not near bottom), and herring form massive schools.