Whales refer to both the baleen whales and toothed whales, and the two subgroups differ only in dentition. Dolphins are made up of marine dolphins and river dolphins which, as their names suggest, are differentiated by their respective habitats. Whales and dolphins are classified under the group of marine mammals known as cetaceans. The two share many physical and behavioral characteristics including the fact that they spend their entire lives in the water and give birth to live young. Although there are similarities, dolphins and whales are different. Most people have a misconception that the main differentiating factor that separates whales from dolphins is size. Whales are thought to be larger than dolphins, but in reality, some dolphins exceed some whale species in size, such as the orca.
Difference in Appearance
Both whales and dolphins have a body shape that is similar to that of fish, a necessary adaptation for life in water. Most dolphin species have well-defined dorsal fins which are used for stability when swimming. A few dolphin species have small dorsal fins. Whales, on the other hand, have tiny (relative to their body size) dorsal fins which are found near the tail fin. The dorsal fin is absent on the beluga whales.
Difference in Size
The smallest of all dolphins is the Maui’s dolphin with adult individuals averaging 5.7 feet in length and about 120 pounds in weight. On the other end of the size spectrum is the orca which is the largest dolphin species. Adult male orcas can grow to be 26 feet in length and weigh an average of 6.6 tons. To put the size difference into perspective, the dorsal fin of adult male orcas is longer than the body length of adult Maui’s dolphin. Some orcas of exceptional size can be more than 30 feet in length and about 10 tons in weight. However, even the largest dolphin, the orca, dwarfs in size when compared to whales. As an example, the common minke whale, which is preyed on by the orca, grows to about 10 tons in weight. The sperm whale, the world’s largest toothed carnivore weighs between 25 and 50 tons. However, the largest of them all, the blue whale weighs between 50 and 150 tons and can grow to over 100 feet in length. The blue whale’s tongue alone is heavier than many adult dolphins, weighing as much as 3 tons. Whales of small size also exists an example of which being the dwarf sperm whale which is the smallest of all whales. Adult dwarf sperm whales are 9 feet in length and can weigh as much as 600 pounds.
Difference in Teeth
All dolphin species have teeth and adults have between 58 and 94 teeth. The dentition of dolphins is perfect for its diet as all dolphins are predators, feeding on fish, squid, and other marine animals. The teeth are conical and relatively sharp, a design that is excellent in biting but poor in chewing. On the other hand, some whales have teeth while others have bristles. Only two types of whales are known to have teeth, and these are beaked whales and sperm whales. All other whales are known as baleen whales which have keratin bristles in place of teeth which they use to filter out krill and other tiny organisms that make up their diet.
Difference in Diet
All baleen whales feed on tiny organisms, with krill and plankton making up the bulk of their diets. These whales also feed on small crustaceans and tiny invertebrates. When feeding, baleen whales gulp huge volumes of water in their massive mouths and pushing out the water through the baleen teeth using their powerful tongues, filtering the tiny organisms. Toothed whales feed on larger organisms including fish and squid. The sperm whale feeds primarily on squid and is thought to prey on the colossal squid. Fish and squid are the chief dietary items for dolphins. The dolphins use numerous tactics to capture their prey, and the most common one is hunting in groups. Larger dolphins such as the orcas and false killer whales go for larger prey items. Orcas are classified as apex predators in all the habitats that they are found. Fish, seals, sharks, and even whales are among the animals that are preyed on by the orca.
Difference in Intelligence
The brain size is one way of deducing the intelligence level of an animal and dolphins have some of the largest brains relative to their body size. The orca has the second-largest brain of any animal, with only the sperm whale having a larger brain. The orca’s brain size is impressive considering that it is larger than that of baleen whales which are many times the orca’s size. A study done on dolphins has established that these animals are self-aware after passing the mirror test. The test involves presenting a mirror to an individual and is popularly done on primates. As a manifestation of their high cognitive abilities, dolphins can learn basic tricks which make them popular in water parks.
Whales are also believed to be intelligent, specifically the toothed whales. The brain size as well can be an indication of the level of intelligence in an animal and no animal on the planet has a brain that exceeds that of the sperm whale in size. The belief of high intelligence in whales is based on the presence of spindle neurons in the brains of whales. These neurons were once thought to only exist in the human brain. However, due to their large size and remoteness of their range, few studies have been carried out to look into the level of intelligence in whales.
Threats and Conservation
Whaling and overfishing are the primary threats to the existence of dolphins and whales in the world. The effects of whaling were detrimental to whale populations around the globe with numbers in some species dropping by as much as 90% in less than a century. Some species such as the blue whale were driven to near extinction by the indiscriminate whaling. However, intense conservation efforts and the ban on whaling which was enacted in the mid-20th century has resulted in whale populations record a significant increase in the recent few decades.