For the Bottlenose, Social Groups = Safety
Of all sea animals, the Bottlenose dolphin is perhaps most beloved … and especially by hungry sharks! Dolphins are in fact Selection #1 on a shark’s dinner menu.
Against a large shark, the benign Bottlenose might seem a helpless target. But have you ever seen a lone dolphin in the wild? That would be rare. It’s more likely you’ve run across them traveling in social groups, or pods, this is how bottlenose protect themselves. The larger the pod, the more protective their “safety in numbers” approach. Typically a pod consists of between 10 and 30 members but may be much larger, depending on food availability and the number of young.
Because oceanic dangers are ever-present, Bottlenose don’t really sleep, instead semi-napping in 30-minute intervals. When fully awake, their keen eyesight and intelligence telegraph danger in numerous ways.
Auditory Communication Works Best. Each pod member uses the sphincter muscles of its blow hole to produce a unique high-pitched whistle. This signature whistling, developed shortly after birth, tells others in the pod that it is present, where it is, and perhaps its situation. Particularly at night or in murky waters, the Bottlenose makes clicking sounds that bounce from objects to its forehead area (the melon) for interpretation. If this echolocation technique reveals impending danger, the Bottlenose will warn others using pulsed squeaks or click trains.
Escape a Limited Option. Large sharks generally cruise at a leisurely 1.5 mph (2.4 km/h). While their maximum swimming speed has seldom been measured, a Blue shark has been tracked at 24.5 mph (39.4 km/h), with bursts of over 40 mph. The short-finned Mako shark is fastest, with speed spurts over 60 mph.
By contrast, the Bottlenose usually swims at from 3-7 mph (5-11 km/h). During bursts, its speed can increase to 18-22 mph (29-35 km/h) but is strenuous to maintain. Nor can the Bottlenose match the shark in the sharpness or number of its teeth. Therefore, when a shark is very near, Bottlenose are more likely to resort to group aggression rather than flight. Pod members use their snouts to hit the shark repeatedly, either on the stomach or against the gills. In some cases this has even caused the death of the shark.
So… keen eyesight, impressive agility and high speed all help Bottlenose dolphins to protect themselves from predators. But, as in human society, there’s no substitute for friends who have their backs.