Learn about different kinds of fish. Fish populate different kinds of aquatic environments. This type of craniate organisms is considered a truly significant resource for millions of people all across the Globe, representing mainly a virtually unlimited source of food and economic profit. Researchers have reached the conclusion that there are approximately 32,000 different kinds of fish, living in diverse ecosystems worldwide.
Hagfish- These odd-looking kinds of fish resembling a snake have a long, thick body. Hagfish have a weird, unique particularity: they are known as the only living, breathing creatures which are endowed with a fully-functional skull, but lack a vertebral column. Moreover, their body structure is quite similar to the one displayed by their fossilized ancestors from 300 million years ago. They usually consume aquatic worms, as well as dead marine organisms, often exceeding their own body size.
Lampreys- These kinds of fish are more evolved than hagfish, their distant relatives, but still different from most types of fish that we are familiar with. Their name stands for â€œstone licker,â€ an inspired nickname referring to the way in which they eat. Lampreys have no jaws and they use their scary funnel-shaped mouth with lots of teeth to absorb the blood of their victims (usually other species of fish). They also display a cartilaginous skeleton and recent studies indicate that this peculiar species is greatly impacted by pollution and human intervention.
ChondrichthyesÂ (also known as cartilaginous fish)- As their name suggests, these kinds of fish also have a cartilaginous skeleton, but their shape and body size is quite similar to the ones that we are used to seeing on a daily basis on TV or in different aquatic ecosystems. This category includes the much-feared sharks, some of the most ferocious swimming predators which usually can be found in temperate and tropical climates. As a curiosity, these kinds of fish lack bone marrow and ribs, but do have scales, nares, fins and a chambered heart.
Osteichthyes (also called bony fish)-This is the last category of fish, a very diverse and ample one, taking into consideration that it comprises no less than 28,000 different kinds of fish, part of approximately 480 different families. A solid skeleton with bony and not cartilaginous structure is the main distinctive feature, which separates this large group from other types of fish anteriorly described. They maintain a perfect balance in a certain aquatic environment due to their swim bladders and, unlike their primitive relatives, Osteichthyes can distinguish colors. While some species of bony fish display a simplified version of fully-functional lungs, other breath though their skin or intestines. Also, their body temperatures is not constant, it varies a great deal based on the temperature of their ecosystem. The size and the structure of different internal organs vary a great deal from one species to another. As a major curiosity, several kinds of fish generically called Osteichthyes, donâ€™t actually have a stomach.Â Bony fish live in marine environment and in fresh water. A bony fish can reach a considerable length (approximately 3 meters) and weight (up to 300 kilos). Oarfish and ocean sunfish are two of the most representative kinds of fish listed in this category.