Determining the overall size of dolphins can be a difficult task because there are numerous species and each species of dolphin has characteristics that make them unique from other dolphin species; however we can look at a couple of the dolphin species to give you a general idea of these differences in regards to size and weight.
As a whole there are currently over 40 known species of dolphin that have been recorded so far.
The smallest known dolphin is Maui’s dolphin which is known to grow to lengths of around 5 1/2 ft. at full maturity and weigh slightly over 100 lbs..
This dolphin is an extremely rare species of dolphin that can be found near the shore of North Island in New Zealand.
In comparison the largest known dolphin is the killer whale which can grow to lengths of up to 30 ft. long and weigh as much as 12,000 lbs..
Unlike Maui’s dolphin the killer whale can be found throughout various oceans around the world.
While not always the case size can have a direct influence on where dolphins can be found living throughout the world.
For example some smaller species of dolphin can be found traveling in and around coastal waters where they are less likely to face threats from potential predators while larger dolphins may venture out further into the offshore ocean far from coastal waters.
Predators for the dolphin species may include killer whales and sharks; and yes killer whales do hunt other dolphin species for food.
Size can also play a role in the dolphins ability to stay warm in cold climates.
Larger species of dolphin are better able to displace heat throughout their body while using fewer calories to do so.
Killer whales for example (the largest of the dolphin species) can be found traveling throughout the Arctic and Antarctic waters while Maui’s dolphin and the popular bottlenose dolphin prefer to stay in warmer climate waters.
In addition to staying near coastal environments small dolphins are also known to travel in large groups in order to protect themselves from predators.
Depending on the dolphins species dolphins are known to consume anywhere from 2% – 10% of their body weight in food on a daily basis.
Lastly, size does not always determine the types of food a dolphin is likely to eat.
While it is true that the killer whale can consume a variety of marine mammals as well as fish and squid, most dolphins stick to a diet that consists of fish, squid, octopus and various crustaceans regardless of their size.
Since all dolphin species possess echolocation they can use this highly important ability to navigate the ocean, search for prey and get an early warning sign for nearby predators looking to turn them into a meal.
By combining their excellent sense of hearing with the use of echolocation dolphins are both excellent hunters and navigators making them one of the most advanced aquatic animals alive today.
Note: For more information on the various species of dolphin check out the toothed whale suborder.