How do dolphins communicate at night? With their SONAR phones!
Okay, I am joking…dolphins don’t use phones. But by now in this ecosystem series, we should all know that dolphins are odontocetes (toothed whales) and that they have the ability to echolocate. This echolocation process occurs through the melon, which is a large, fatty organ located just in front of the blowhole. Depending on the toothed whale species, the melon can be more pronounced, or less distinct. For the short-beaked common dolphin (Delphinus delphis), their melon is smooth and rounded, but not overly large compared to other toothed whales. This melon is well defined due to the deep crease that separates it from the beak.
Short-beaked common dolphins (Delphinus delphis) get their name because they are the most abundant and widely distributed species of dolphin in the world and for their shorter, stubbier beaks. Common dolphins are known for their striking and lively behavior. They have a sleek, streamlined body that helps them move gracefully through the water. One of their most distinctive features is their hourglass pattern, a unique marking on each side of their body. The pattern consists of a light yellow to golden-tan color that forms an hourglass shape, with darker, often grayish tones above and below it. Typically they range from 6 to 8 feet in length and weigh on average only about 170 lbs. Can you think of a dolphin species that you’ve learned about that weighs more?
These acrobatic dolphins are not just known for their beautiful appearance, but also for their incredible speed. Common dolphins are one of the fastest dolphin species, reaching speeds of up to 37 mph! That’s faster than cars drive through a school zone. Short-beaked common dolphins are generalists, meaning they eat a wide variety of prey, which helps them adapt to different environments. Their diet mainly consists of small schooling fish, such as anchovies, sardines, and mackerel, as well as crustaceans and squid. These dolphins are primarily nocturnal foragers, taking advantage of the night when many prey species migrate closer to the surface. They are skilled hunters and can dive to impressive depths, often exceeding 650 feet (200 meters), to find food in deeper waters. The predators of short-beaked common dolphins include large sharks, such as great white and tiger sharks, as well as orcas, which hunt them in certain regions.
Just like humans talk to each other, short-beaked common dolphins use sounds to communicate! They are very chatty, and make three main kinds of sounds: clicks, whistles, and burst pulses. The clicks help them find food and objects around them, like using a flashlight in the dark. The whistles are their way of talking to each other, helping them stay connected with their friends in their pod. The burst pulses are faster sounds that they will use to show excitement or to warn others. Can you distinguish the sounds in this recording?
The Whalemobile team has been lucky enough to encounter large pods of short-beaked common dolphins in the Gulf of Maine, and sometimes they are so chatty we can hear their whistles from the boat! With that being said, short-beaked common dolphins aren’t as commonly seen on whale-watching boats in the Gulf of Maine because they prefer warmer, deeper, offshore waters rather than the cooler, nutrient-rich coastal areas where our whale-watching tours operate. In recent years our team has had more sightings of this dolphin species in the Gulf of Maine than previous years. Can you think of a reason why this may be the case? Email us and let us know what you think!
Dr. Tammy Silva studies the common dolphins around the Stellwagen Bank National Marine Sanctuary. Click here to see an article about her research!
At The Whalemobile, we believe people protect what they understand—so we bring ocean science to life through stories, hands-on learning, and by bringing a life-sized whale in schools and libraries. To learn more about our programs, visit our website at www.thewhalemobile.com.