Question 2 of 21

How are bottle-nosed dolphins generally perceived?

... Most people think of bottle-nosed dolphins as intelligent, friendly creatures, who have even gone as far as to save shipwrecked sailors by leading them to land. However, marine biologists have discovered a different side of dolphins, which can lead them to kill.

Question 3 of 21

Who was the marine biologist who led the group that discovered aggressive dolphins?

... Richard Connor led the group that studied the aggressive nature of dolphins.

Question 4 of 21

In which decade were most of the new dolphin behavior discoveries made?

... Most of the discoveries about the dark side of dolphins were made in the 1990s.

Question 5 of 21

Which group of animals usually forms social alliances?

... Females are generally the ones who form social alliances. However, among dolphins, it is the males who form alliances. In some cases it was observed that several smaller dolphin groups united to form one large "super-gang."

Question 6 of 21

How long do some male dolphin alliances last for?

... Some dolphin bonds were observed to have lasted more than 10 years.

Question 7 of 21

Why do male dolphins form alliances?

... Male dolphins bond for sexual purposes: to stalk potential mates and fight off rival males. The male groups kidnap a female dolphin and hold her captive in order to mate with her.

Question 8 of 21

Up to how long might a female dolphin remain in male captivity?

... Females were observed to have remained in captivity for up to one month.

Question 9 of 21

What do dolphins to do females to prevent them from escaping?

... Male dolphins bite and ram the females to prevent them from escaping.

Question 10 of 21

What spurs on male dolphins to capture females?

... Female dolphins can be quite promiscuous and have been observed to be very sexually active. Females often want to mate with as many males as they can. Therefore, male gangs are a way of male dolphins preventing females from reproducing with rival dolphins, ensuring that their group will reproduce.

Question 11 of 21

Where have super-gangs of dolphins been observed?

... Although dolphins have been observed in all of these places, super-gangs have been observed only in Shark Bay, off the coast of Western Australia.

Question 12 of 21

What ability do female dolphins have with regard to mating?

... Female dolphins use strategies to control which male dolphin they conceive with. They do this because they will spend many years rearing a single calf, so they want to make sure it is from the best male.

Question 13 of 21

How long do female dolphins usually spend raising a single calf?

... Dolphin calves spend between three to six years with their mother. The mother will remain sexually inactive during this time.

Question 14 of 21

Which animals were dolphins killing hundreds of in 1990?

... Researchers found hundreds of dead porpoise off the coast of Scotland. Autopsies revealed the murderers were bottle-nosed dolphins.

Question 15 of 21

What caused the death of the porpoise?

... It was found that the dolphins had battered the porpoises, leading to fractured bones, ripped tissue and bruised organs.

Question 16 of 21

How did scientists discover that bottle-nosed dolphins were behind the porpoise killings?

... The spacing in the teeth marks found on the porpoises matched perfectly to that of an adult bottle-nosed dolphin.

Question 17 of 21

Why did the dolphins kill the porpoises?

... It is unknown why they did, since they do not compete for food or mates. Perhaps they just did it on porpoise.

Question 18 of 21

What other dolphin killings have been documented?

... Baby bottle-nosed dolphins began to wash up on Scottish beaches, bearing wounds similar to those of the porpoises. It was concluded in 1998 that bottle-nosed dolphins were behind the killings of their own babies.

Question 19 of 21

How old were the baby dolphins that were killed?

... The dead baby dolphins were all less than a year old, an age at which they are usually under the full-time care of their mothers.

Question 20 of 21

Within how long can female dolphins become fertile after losing an infant?

... Female dolphins are sexually inactive during the years they raise their calves. However, they can be ready to mate within one to two weeks of losing their calf. This is thought to be the reason why dolphins killed baby dolphins. By doing this they destroyed rival offspring and caused the females to become sexually active again so they could breed with them.

Question 21 of 21

What is other speculation as to why dolphins killed the porpoises?

... Some think that bottle-nosed dolphins attacked the porpoises as target practice, others because they confused them with baby dolphins in the murky waters, due to their similar size.