Saturday, October 23, 2004

Interesting Dolphin Facts

Here are some interesting dolphin facts I picked up from the National Geographic Channel documentary last night. After a busy week, it was a treat to be alone and delight in learning about something completely different from my line of work/study.


Interesting Unknown Fact before Delving into Facts
Killer whales (a.k.a. orcas), pgymy killer whales, and pilot whales are actually dolphins. Their names are misleading. Killer whales are cousins to the well-known bottlenose dolphin species. Killer whales prey on their smaller cousins and are one of the few mammals known to kill smaller mammal species, including their smaller cousins.

Ridor was wrong about them having violent sex. I took his word for face value until I watched this documentary. Dolphins actually have frequent casual sex, caressing, and petting. This is often a social tool, not just for mating purposes. Dolphins are very affectionate, not vicious like Ridor said. I will address dolphins' viciousness in another area soon.

Societal Structure
Dolphins' societal structure is very similar to our structure and parallels in many areas.

Let's get back to Ridor's subspecialty and area of interest: aggression. Dolphin aggression, which has been studied by a team of scientists in Shark Bay, Australia for years, indeed exists. Dolphins, although highly individualistic, can form "gangs" as needed when fighting over females (for mating purposes) in order to capture females. They do not hurt the females. They merely fight with other male dolphins over females within this complex social system. Scientists have collected data that document dolphins' intelligence in understanding and respecting social structures and roles within this complex social system.

A visible jaw clapping observed is a sign of danger and trouble. It's like an outright threat. Think of this as a person raising his fist, threatening to fight. Male dolphins ram heads, bite, blow hard with their flukes, and sometimes band together to attack one identified dolphin. Why? To capture that dolphin's female captive or to take care of business.

Females can be held hostage by males for up to few years. Males often create alliances when holding a female captive. These alliances can last a dozen years or so. One guards over the female while the other male goes to hunt, eat, etc. They take turn guarding the female. While both males are together with the female, the female is held captive between these two males to prevent the female from escaping or being kidnapped by other male alliances. When one wants to kidnap, the males do popping noises to call out other males. If others appear, they sometimes create super alliances to supersede and capture the female of another alliance. Or, these smaller alliances merge to create a super alliance for protection. This is similar to the "popular" crowd in high schools. Scientists call this the "WOW" crowd. (I personally found this choice of word amusing.)

One reason why males hold females captive is to restrict the number of mates the female dolphin has. But, the females often have strategies to increase mating partners. As soon as they bore babies, females are not available for few years and are usually left alone by males who look for females to hold captive. They may exist within superalliance groups but are left alone as far as sex and hostage is concerned. A benefit of this is that the alliance or pod helps the baby dolphin be protected from outside predators. The males in these pods also help protect the females and their calves from immature young male dolphins who do not understand their position in this complex society yet. These young ones often harass the females and their calves. The older ones help ward them off.

In instances when there isn't such protection or the older males become jealous, the male dolphins may band together to incessantly harass the female and the calf. The calf may be killed in order to win over or recapture the female. When there is no calf present, the female becomes sexually receptive once again. Otherwise, the mothers just fight off those who try to harm her calf or call in members of her super alliance with her popping sounds to gang up on these intruders, kidnappers, and murderers-to-be.

You may already know by now that dolphins are very intellectual creatures who have a highly-complex social structure.

They use their intelligence to their advantage while hunting. They come up with innovative hunting techniques. Techniques vary from one dolphin to another. Some have mastered specialty techniques such as hunting in shallow water or shorelines using hydroplaning. Some use echolocation to find small fish buried deeply in the sand and accurately stick their snout into the sand to capture that fish. Others have chasing and catching techniques such as banding.

One interesting fact is that many play with their food "like ragdolls" before eating. Dolphins do not steal food from each other. This may be due to the societal structure and social benefits such as trust or avoiding conflicts.

Smaller subspecies of dolphins need to be defensive against their larger cousins such as the killer whales. They use their judgment in knowing when to be "noisy," using their sonar language, when to turn off their sonar, using silence and actively listening for their predators, and banding together in larger superalliances/pods.

As one can see, there is much more to these sweet-looking, communicative, and highly-intelligent mammals humans often identify with.