The hourglass dolphin is a rare species of dolphin that can be found swimming in the Antarctic and Sub Antarctic oceans.
This dolphin is so rare in fact that it is the only cetacean that has been classified as a species based solely on feedback from witnesses.
Only a dozen or so hourglass dolphins have been examined, so most of what is known about this species comes from the rare observations uncovered by those who have spotted it.
In terms of appearance these dolphins have a distinct black and white pattern which resembles the design of an hourglass, which explains how they got the name “hourglass dolphin”.
Most of the body is black, however they have two patches, one that runs from the beak to the dorsal fin and another that starts at the dorsal fin and runs down to the tail.
Both patches are connected by a thin white strip that is located near the dorsal fin.
Their bodies are stocky yet short in length (less than 6 ft) and from the few that were examined they can weigh in excess of 250 lbs.
They have a large dorsal fin and their tail often appears keeled.
At times these dolphins can be seen feeding in large groups near or at the surface of the water.
Like other species of dolphin echolocation is believed to play a large role in their ability to navigate the ocean and find food.
Social Structure and breeding habits
Hourglass dolphins appear to prefer traveling in small pods composed of 10 or less dolphins although they have been spotted traveling in much larger aggregations.
They can often be seen feeding with other groups of cetaceans such as pilot whales, minke whales, southern right whales and fin whales among others.
They also appear to enjoy bow riding which involves riding the crest of waves created in the ocean.
Little is known about the breeding habits of the hourglass dolphin, however it is believed that baby dolphins are nursed by their mothers for 12 – 18 months before fully separating from their dependency on their mothers milk.
Research done on female hourglass dolphins suggests that their average gestation period is 12 – 13 months.
The age of sexual maturity and lifespan of these marine mammals is unknown.
Currently it is estimated that there are more than 140,000 hourglass dolphins in existence.
Due to their environment and location these dolphins rarely face threats from getting caught in fishing nets and are not known to be hunted by whalers.
10 Engaging hourglass dolphin facts
- The hourglass dolphin makes up one of around 40 known dolphin species and one of around 80 known cetaceans in existence today.
- Because these dolphins are marine mammals they are warm-blooded, breath air, produce milk to feed their young and give birth to live dolphins (instead of laying eggs).
- The scientific name for the hourglass dolphin is, “Lagenorhynchus cruciger”.
- The only potential natural predators of the hourglass dolphin is a pack of killer whales.
- At under six feet long the hourglass dolphin is about the size of an average adult male.
- These marine mammals are commonly found in cold waters ranging from 32 – 55 degrees Fahrenheit (0 to 13 degrees Celsius).
- Although the hourglass dolphins population size is unknown it is considered a protected species along with all other cetaceans and hunting these marine mammals is illegal.
- Because these marine mammals hunt near the surface of the water and consume prey that is also commonly hunted by seabirds researchers often look for flocks of seabirds to detect potential locations for where a group of hourglass dolphins may be eating and/or hunting for food.
- Despite accidental catches due to fishing nets and the best efforts of researchers these dolphins are rarely ever captured and information regarding this species has been difficult for marine biologists to obtain.
- Although they prefer small pod sizes on rare occasions these marine mammals have been spotted in groups of 60 to 100 dolphins.