(Stenella coeruleoalba)
Introduction
You may hear the Striped Dolphin referred to as streakers in some locations. This is because they are able to move very rapidly to avoid boats in the water. Their coloration gets them plenty of attention. It is also a way to distinctively tell which species of dolphin you have seen.
Description
As the name indicates, these dolphins have an identifiable striped pattern on their body. They are blue with white stripes that are found on the lateral body areas as well as the dorsal. The stripes can also be light gray or cream colored. They have darker coloring on the sides than underneath. The colors often depend on the habitat so that they can blend in well with their surroundings. The stripes and clored patterns become more evident as the Striped Dolphin gets older.
They also have a long beak with a tall dorsal fin. They feature dark black stripes on the long, narrow flippers. They can grow to a length of approximately 9 feet. They can weigh up to 350 pounds. The females are usually smaller with an overall length of approximately 8 feet and they weigh about 20 pounds less than the males. The body is medium sized and very detailed for them to easily move through the water. They have from 43 to 50 pairs of teeth that are small but sharp and cone shaped. They are located both in the upper and the lower jaws.
Distribution
The Striped Dolphin is found living in warm bodies of water around the world. This includes the oceans and the various tropical seas. They also live around the Gulf of Mexico. They are diverse in their habitat as they live both in shore and off shore. They tend to prefer water that ranges from 52 degrees Fahrenheit to 84 degrees Fahrenheit. They are most likely to be found around convergence zones and areas of upwelling.
The movements of the Striped Dolphins are very interesting to experts. They have found them to be outside of typical ranges. Perhaps it is due to lack of food or habitat destruction in their normal locations. Some of the areas where they have been spotted include Prince Edward Island, the Southern portion of Greenland, the Kamchatka Peninsula, and Faroe Islands. They don't seem to have found their way to the colder waters that are around Alaska, so such reports are false.
Behavior
The Striped Dolphin is the only species that takes part in roto-tailing. This is the process of leaping very high out of the water. While it is out of the water, they rapidly rotate the tail while in midair. The jumps can be up to 20 feet in the air! This particular dolphin is extremely active, and they are known to take part in a variety of maneuvers. They may bow ride, breach, and they are quite vocal. They make a variety of whistling and clicking sounds to communicate with each other. All dolphins do this, but the Striped Dolphins seem to engage in it much more.
The size of a pod of Striped Dolphins can range from just a handful to more than 1,000. They do have larger pods though than most dolphins. The average is from 100 to 500 members. There are plenty of types of schools though for them including those with juveniles, those with breeding adults, as well as those that include non-breeding adults. With such distinctions the dolphins will move around to various pods at different times in their lives.
For example, calves usually move to the juvenile school when they are a couple years of age, after weaning. Juveniles may move to the non-breeding adults before they actually transition to the breeding school. What is interesting is that the numbers tend to remain very equal between the non-breeding and breeding schools. The complexities of these movements in the various schools may contribute to why more communication takes place.
Feeding
They will take the various opportunities that come along in their environment for eating. They tend to consume large amounts of bony fish, crustaceans, and cephalopods. The types of food they dine on though will vary based on the region they live in. They tend to look for food around the continental slope where the ocean floor has a steep element to it. They can dive up to 2,300 feet to get food.
Reproduction
The females are ready to mate between the age of 5 to 13. Males are ready to mate at a later time from 7 to 15 years. Studies show that the length of the Striped Dolphin plays more of a role in when they are ready for mating than age alone. Typically, when they are about 7 feet long they are ready to mate.
There isn't a great deal of information known about the mating habits of these dolphins. They give birth to one calf in the summer which is about 12 to 13 months after mating. The young can be up to 3 feet in length at birth. The females will typically only give birth once every 3 or 4 years. The average lifespan for Striped Dolphins is 50 to 58 years.
Conservation Status and Threats
The listing with the IUCN for the Striped Dolphin is low risk, but it is classified as conservation dependent. This means that without a conservation plan of action in place, they will move into the classification of being threatened or endangered within the next 5 years. Some of the common problems for decline in the wild including commercial fishing, loss of habitat, and these dolphins being killed for their meat.
The conservation efforts in place focus on improved fishing methods that will lower the risk of the Striped Dolphins getting caught up in their nets where they become injured or they die. Preserving habitat by reducing noise and pollution is also a key part of conservation. This is one species of dolphin that is rarely struck by boats so that isn't a big concern. Laws to limit or prohibit killing them for meat is one avenue that can be explored.
