The bottlenose dolphin is a large, grayish aquatic mammal that visits the lower and middle Chesapeake Bay in summer.
The bottlenose dolphin has a slender, streamlined body that is grayish in color. Its sides and belly are slightly paler. It has a short, beak-like snouth with a slightly longer lower jaw than upper jaw. It has a blowhole on the top of its head. Bottlenose dolphins can grow to 12 feet in length and weigh 300 to 400 pounds.
These dolphins are found mostly in warm, salty open waters, but also visit the lower reaches of rivers and harbors. They travel in small schools, or “pods,” of 2 to 15 dolphins. They can feed in fresh waters for short periods of time.
Visits the Chesapeake Bay in summer, and is most often seen in the lower Chesapeake Bay near Cape Charles and the James and Elizabeth rivers. Some dolphins may venture as far north as Baltimore Harbor, the Chester River and Washington, D.C.
Bottlenose dolphins feed mostly on fish such as spot, croakers, menhaden and silver perch, but will also eat shrimp, squid, crabs and other invertebrates. They uses their teeth to grasp prey, then swallow it whole.
Sharks, such as bull sharks, are dolphins’ greatest predators. Humans threaten dolphins through pollution and recreational fishing gear.
Dolphins use sound to communicate with other dolphins, navigate through the water, watch for predators and find prey. Sounds include clicking, creaking, squeaking and whistling. Each dolphin is believed to have its own unique whistle. Puffing and hissing sounds can be heard when they exhale through their blowholes.
Mating occurs throughout the year. Females give birth to one calf every 3 to 6 years. The gestation period lasts about 12 months. Calves are born in the water. During the birth, an assisting dolphin (which may be either male or female) remains close to the mother. This assisting dolphin is often the only other dolphin allowed near the newborn calf. Calves begin nursing within several hours of birth. They feed on their mother’s milk for 18 months. Females reach sexual maturity between 5 and 12 years old, while males mature at 10 to 12 years old. Bottlenose dolphins usually live about 20 to 25 years, but some may live longer than 40 years.