Freshwater fish used as food in many parts of the world.
Many freshwater fishes are also popular as food.
Bacteria occur in a wide range of shapes, including spheres, rods and spirals.
A hydrothermal vent is a fissure in the planet's surface through which geothermally heated water erupts.
Jellyfish are free-swimming marine animals, a species of Cnidaria, the most ancient group of Eumetazoans.
Physical properties, as well as the flora and fauna of the ocean change with depth.
This animation demonstrates the most important seas and bays.
A group of fish characterised by a cartilaginous skeleton, well-known species include the great white shark and the great hammerhead shark.
Living fossil, important stage in the evolution of tetrapods.
Atmospherical nitrogen is bound by bacteria and used by living organisms in the form of various compounds.