A Delaware beach vacation just does not seem complete until you witness the playful passersby along the coastline: the dolphin. The charismatic cavorting of these creatures just off the shoreline never fails to draw crowds of excited observers who watch them frolic about in the Atlantic.
This year’s annual dolphin count, conducted by the Marine Education Research and Rehabilitation (MERR) Institute, yielded its highest numbers yet, with more than 800 spotted in a two-
hour timeframe.
While bottlenose dolphins are typically the most common sight for elated visitors, the local waters are teeming with no fewer than seven species that inhabit the area and it’s time to give some attention to other equally fascinating creatures that may not have the same level of popularity as their bottlenose brethren.
Common Dolphin (Delphinus delphis)
Also known as the Short-beaked Common Dolphin, the Common Dolphin is a frequent visitor to the northeastern U.S. coast. Distinct for its striking hourglass pattern and vibrant dark-and-light coloration, these dolphins are quite social and often seen in large congregations (sometimes in the hundreds). In the open ocean, they can be seen frequently leaping and riding the bow waves and wakes of boats (and whales!). Common Dolphins can typically be found along underwater ridges and continental shelves where upwelling (in which deep nutrient-rich water rises) occurs and prey is plentiful.
Atlantic White-sided Dolphin (Lagenorhynchus acutus)
Easily identified by its distinct white and tan blaze on its side, these dolphins are often found in the cold, temperate waters off the northeastern coast and are quite the acrobatic performers as well. They will travel in groups and are often spotted in the company of other cetaceans such as white-beaked dolphins, bottlenose dolphins, and pilot whales.
Risso’s Dolphin (Grampus griseus)
Named after French naturalist Antoine Risso, these unique dolphins have a stout body and a blunt head. Typically gray to black, they are often covered with markings (scars and scratches) from social interactions and encounters with prey. They are commonly found in deeper offshore waters where they feed on squid and are known for their deep diving capabilities (over 1,000 feet) and can hold their breath for up to half an hour. Fun fact, the first-ever documented rescue and release of a Risso’s dolphin (nicknamed Rocky) took place at Cape Henlopen State Park 20 years ago. For those with an Amazon Prime subscription, you can see Rocky’s journey in episode 11 of the fourth season of Sea Rescue, titled “A Rocky Road to Recovery.”
Striped Dolphin (Stenella coeruleoalba)
Among the most abundant and widespread dolphins in the world, Striped Dolphins are distinguished by their sleek bodies and prominent blue and white stripes from their eyes to their tails. Like their cousins the Common and White-Sided Dolphins, they are capable of performing leaps and spins in the deep ocean, where they feed on fish and squid. They are so agile, in fact, that they have crafted a unique maneuver called roto-tailing, in which they leap out of the water and rotate their tail while airborne. Here is a video displaying some of their aquatic acrobatics.
The northeastern United States’ coastal waters are home to an array of dolphin species, each with unique behaviors and characteristics that often bring delight to observers on land and at sea.
MERR provides rescue and response for stranded marine animals that occur throughout the state of Delaware. MERR is a 501(c)(3) organization dedicated to the conservation of marine mammals and sea turtles and their habitat. If you notice a marine mammal or sea turtle in distress in Delaware, please contact MERR’s 24-hour hotline at 302.228.5029.
Rob Rector has served as naturalist and board member for 20 years, is a certified Protected Species Observer, and leads weekly dolphin observation tours that use citizen science to gather information on our local Bottlenose Dolphin populations.
