It’s very likely that you are aware that dolphins (cetaceans) are one of the smartest animals in the world. One sure way to identify intelligence in any animal is to witness that creature engage in the use of tools.
Sponging dolphins have been seen using sea sponges as tools for in the quest for food. Dolphins are equipped with echo-location and speed. Then, why do they need assistance from a sea sponge? Continue reading to find out!
The first sponging dolphins were a group of Bottlenose dolphins spotted in 1984 on Shark Bay, Western Australia. For the first time were cetaceans seen displaying this type of behavior. The researchers noticed that every time these dolphins were ready to feed, they will first yank a Marine Basket Sponge from the sea floor.
The scientists’ explanation for this behavior was that the dolphins were carrying these sponges on the tip of their beaks (rostra) for protection (Science). You see, in this part of the world the sea floor is not soft as it is in other places, such as the Bahamas. They have to contend with pieces of broken coral and rocks that can injure the unprotected beak (rostra).
When we think of dolphins, bottom feeders doesn’t come to mind, but fast and agile swimmers that have little problem snaring a fish from the water. Then why do some resort to bottom feed, and with the help of a sea sponge at that.
Part of the answer lies in how their echolocation system works. It is designed to pick up on an acoustic signal given off by a fish’s swim bladder. The particular bottom-dwelling fish the dolphins are after lack a swim bladder. They don’t possess the gas-filled chamber that allows the fish to control its buoyancy in the water. This means these cetaceans are not able to echo-locate these fish.
Since they are not able to locate these fish using their sonar, these dolphins use the sea sponge to disturb the sea floor and making their prey flee. The second reason they chose to bottom feed for these particular fish is they happen to be very nutritious. Their high nutritional content makes it worthwhile for the cetacean to go that “extra mile” to eat.
It’s A Girl Thing
You will not be able to find a dolphin make use of a sea sponge anywhere except for Shark Bay in Western Australia. One in about nine dolphins will engage in sponging, and the vast majority are females. Genetic testing has revealed that this skill is primarily passed from mother to daughter (Discover).
In fact, the first cetacean that was ever witnessed sponging was a female dolphin. She was coincidentally named “Sponging Eve.” The reason for this could be that only daughters come back to their mothers after weaning (APA).
The investigators decided to confirm their observations; using a sponge fixed to the end of a pole they imitated the dolphins’ foraging behavior. They discovered that the same kind of fish unearthed by the dolphins were also being extracted by the scientists’.
When the researchers disturbed the sea floor using the sea sponge, the same fish were combed out – the Spothead Grubfish (Discover). They noticed that as they were ready to use the sponges, the fish were not visible. As soon as they began to disturb the sediment, the fish became visible; when they swam and re-buried themselves, they remained visible.
Great Tool Users
When it came to the amount of time using these sponges, these Bottlenose Dolphins are second only to you and I. They spend over ninety-five percent of their foraging time using these sponges.
These cetaceans will spend 17% of their day sponging – making them the most tool-savvy animal besides human. The Galapagos woodpecker finch sits at second with 10% of their time being used for tool-handling. The chimp and orangutans are situated at third with only 3% of the daily hours handling a tool. They all use tools specifically to find food. (Discover).
Most of us are familiar with how intelligent dolphins are. Their display of problem solving skills using sea sponges leads us to affirm that we are not alone in manipulating our environment in the quest for a specific result.
This use of tools by this select group of Bottlenose Dolphins was first seen in 1984. For the first time, or since has any other animal been known to use a tool as extensively as these creatures have. Initially this bottom feeding behavior was seen to be at odds with the dolphins’ speed, grace and sonar. Thanks to these abilities, dolphins can pluck fish from the water with relative ease.
These cetaceans are lured to the debris-filled sea floor by the high nutritional content of the Spothead Grubfish. They make use of the Marine Basket Sponge to protect their beaks and to expel the fish from the sea floor. These particular fish don’t have a swim bladder – making them undetectable to the dolphin’s sonar.
The female dolphins in this group are the ones that most often engage in this sponging behavior. They pass down their craft mainly from mother to daughter.
Researchers have mimicked these dolphins’ foraging behavior using a sponge. They got similar results as did the dolphins. Which suggests this to be a very effective and reliable method of extracting a certain type very nutritious fish from the sea floor.
This group of dolphins demonstrate their intelligence by the amount of time they engage in the use of a tool – in this case sea sponges. Second only to us, they spend more of their day engaging a tool than any other animal on earth.
It has been shown that sea sponges are a benefit to other creatures as well – including us. We have known, for millennia, how useful sea sponges are. They have been assisting us with many of our daily tasks for a long, long time; now they are on front line helping us find cures for diseases such as cancer and herpes. It is little surprise that another intelligent creature, like the dolphin has also discovered an important use for this amazing creature.
What do you think about the use of sea sponges by this group of dolphins? Can you think of other uses some animal can also come up with? Do you use natural sponges at home? If so, how?
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