The southern right whale dolphin (not to be confused with the southern right whale) is a small – mid-sized dolphin that can be found living in the southern hemisphere north of the Antarctic ocean. As with the northern right whale dolphin, these marine mammals do not possess a dorsal fin and have a white/black two-tone pattern.
The right whale dolphin name comes from the fact that these marine mammals lack a dorsal fin, just like the right whale species. These dolphins are often described as an agile and social species known to perform various acrobatic feats and can be seen travel in pods of up to 100 dolphins with occasional groups expanding to 1000 pod members.
As a species, the right whale dolphin is one of over 40 known dolphin species and one of around 90 known species of cetacea.
Physical Characteristics and Appearance
When fully grown, the southern right whale dolphin measures at around 5 1/2 – 10 ft. long and weighs between 130 – 250 lbs, with females growing slightly larger than their male counterparts. These dolphins have a short beak that slopes down from the forehead and becomes pointed towards the end of the beak.
Unlike other dolphins, the southern right whale dolphin completely lacks a dorsal fin, making it easier to identify within its region. The body is streamlined for low water resistance and is most robust near the center while tapering down towards the head and flukes. The flippers are pointed and small, and the flukes are fairly narrow and short.
In terms of color, the upper body is dark grey to black, and the sides and underbody are white. The black upper body begins just in front of the blowhole and trails down along its back to the flukes while the front of the beak and flippers remain white. The black tone also trails down the upper half of the skull covering the eyes and dipping towards the very beginning of the flipper area before rising back up and arching across the back.
Diet and Hunting Methods
The southern right whale dolphin is known to consume various mesopelagic fish, squid, octopus, and crustaceans. Their primary fish source in their diet is lanternfish and bigeye tuna. During long dives, southern right whale dolphins have been observed remaining underwater for up to 6.5 minutes and diving to up to 200 meters.
Belonging to the dolphin family, these marine mammals possess echolocation, which is likely to help these dolphins search for food, identify potential predators and navigate the ocean at night. Many dolphin species are well known for using echolocation to identify other hunting partners and coordinate attacks. However, information regarding the southern right whale dolphins hunting methods remains fairly limited.
Habitat and Migration
As the name suggests, these dolphins can be found living south of the equator in cool temperate waters north of the Antarctic waters. These marine mammals tend to prefer deep offshore waters where they can dive to depths of 200 meters or more in locations that are between 8 – 20 degrees celsius.
They can be found following the oceanic southern band primarily between 30°S and 65°S and can be spotted in locations such as Argentina, Australia, Brazil, the Falkland Islands, Peru, South Africa, and Uruguay, among other areas south of the equator.
Social Structure and Communication
The southern right whale dolphin can often be seen traveling in groups of fifty to several hundred dolphins, with a few groups expanding to as much as one thousand dolphins. However, the size of the group often depends on the dolphin’s pod and location, and some pods may contain only two to a dozen dolphins.
In addition to traveling together, these dolphins can also be spotted traveling and interacting with several other species of dolphin. They have been observed leaping out of the water, belly-flopping, and lob tailing, among other acrobatic behaviors, and have been described as elegant and graceful swimmers.
The southern right whale dolphin is also a fast swimmer and can move through the water quickly when playing or fleeing from threats. Interestingly their behavior can also vary from one dolphin to another, with some dolphins appearing more playful and outgoing than others.
In certain instances, one group of dolphins may be seen swimming up to boats and following them, while another group becomes shy and cautious when they notice a boat or ship in the area.
Mating and Reproduction
Unfortunately, there is no sufficient data regarding the breeding habits, sexual maturity, or lifespan of the southern right whale dolphin. Newborns have been observed measuring between 30 – 40 inches during birth, with adults growing to lengths of 5 1/2 – 10 ft. long.
In most cases, the primary gestation period for cetaceans is between 10 – 17 months, with most species giving birth after 10 – 14 months. However, no data exists regarding the gestation period of the southern right whale dolphin. It is also likely that newborns are fed milk during their first months of life; however, any information regarding their breeding habits and reproduction process remains speculative and inconclusive without conclusive evidence.
Threats and Predators
The southern right whale dolphin isn’t known to face threats from many predators. However, it is believed that killer whales and local sharks may occasionally attack them.
Regarding human threats, these marine mammals have been known to face threats from accidental bycatches in drifting fishnets and other fishing gear. They have also been hunted in certain locations throughout the southern hemisphere for human consumption, and in some cases, they may also be used as crab bait by fisheries.
The southern right whale dolphin is considered a protected species, and those caught hunting these dolphins may face legal consequences. However, the enforcement of such legal discipline is often dependent on the location they are hunting in, as some areas may be more likely to enforce poaching behaviors than others.