Category: Feeding Behavior.
There are many animals that live on the different biomes of Earth’s surface, and in order to survive, these animals must find innovative ways to feed and ingest nutrition – even in the more difficult habitats. For those living in the water, they are considered aquatic predators.
Malabar grouper (Epinephelus malabaricus) is a suction feeder. © Jon Hanson, UK.
Types of aquatic predation
Aquatic predation is a broad term that covers the various types of feeding methods that underwater creatures use to eat. Eating in water is especially difficult for wildlife because of the density of the water. This means that the several types of animal need to use filter feeding, suction feeding and other methods. Some animals even use more than one method when feeding.
The method of suction feeding requires the predator to eat their prey by sucking it into their mouth. How does this work? The suction feeding animals feed by making their oral cavity expand, which causes there to be a difference in pressure between the internal mouth of the animal and their environment. Because of this pressure, water will begin to flow into the mouth of the predator, which causes their prey to move into their mouth.
Example of suction feeders
An example of a suction-feeding animal is the bony fish – which is known to use a mechanical linkage method in order to expand their mouth and move the food in.
Reef manta ray (Manta alfredi) ram feeding on zooplankton. © Jaine FRA and friends.
Another method of aquatic predation is called ram feeding. It is a way that animals feed that involves the predator moving or swimming around with their mouth open, taking in the prey they are searching out along with the surrounding water. The prey does not even necessarily know that the predator is there, as the prey stays in place and the predator swoops in, closing its jaws around the prey, consuming it.
There are challenges
One challenge that some animals that ram feed face is that the flow of water from their movement can move their prey away, but by moving quickly or by flowing the water through their mouth, the predator can still easily catch its prey.
Indian mackerel (Rastrelliger kanagurta) ram feeding on macroplankton. © Dino V Doorn.
Examples of ram feeders
There are several animals that fit into this category by means of an expandable throat including snapping turtles and baleen whales. There are also sharks and herring that use their gills to move water through their body so they can more easily catch their prey. Some of the animals that use this method even have narrow snouts to use for this method, like garfish and water snakes.
Some don’t do it all the time
While the herrings are not always ram feeders, if they see a school of prey formed, then they have been known to switch to this method. When doing this, they will open their mouths wide and swim, catching the fish inside. After every few feet, they use what’s called gill rakers – something that falls in line with filter feeding.
Pivot feeder, Beige thorny seahorse (Hippocampus histrix). © Nick Hobgood.
The final method of feeding classified under aquatic predation is pivot feeding. The act of pivot feeding is when an animal moves their mouth toward their prey by turning their head up and pivoting their neck joint.
Examples of pivot feeders
There are several types of animals that use the pivot feeding method, such as seahorses and seadragons. These specialized feeding machines can capture prey in about 5 milliseconds – that’s a lot of prey that can be caught in a second! This is why pivot feeders are considered to be the fastest feeders in the animal kingdom.
Antarctic krill using filter feeding to feed on phytoplankton. © Professor Uwe Kils.
Why are they so fast?
The trick is that they have a locking mechanism in their body called the hyoid arch. This arch is located under the animal’s head and it is connected to the urohyal.
A bait ball
A bait ballis a tightly packed, school of pelagic fish. Some of the common fish species that form bait balls are the Sardines. This is a popular way for large predatory fish to have a large meal with little effort. Most of the time, a number of different species of predators will work together to force the fish to form a bait ball. Once the bait ball is formed, it will be an easy meal for all.
Aquatic predation is composed of several methods of feeding, all of which require skill and adaption of the body for animals living under the sea. While each underwater creature has their own category of feeding, they all work to makeup the ecosystem of the underwater life.
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