Ah, schools of fish! Those swirling, shimmering masses of life that can leave you breathless underwater.
When we divers are cruising along a coral reef, a flash of silver often catches our eye. It’s a school of fish – hundreds, maybe even thousands strong – darting and weaving in perfect unison choreography.
These schools aren’t just pretty to look at, though. They’re a survival tactic with serious benefits for their members.
Let’s learn about them
Scuba diving is about the feeling of weightlessness, the vibrant coral reefs, and of course, the mesmerizing underwater ballet of fish. But have you ever wondered why they sometimes swim in loose disordered groups and other times move in perfect unison? That, my fellow divers, is the difference between shoaling and schooling.
School of fish: They are like a traffic jam but with fish. Hundreds, maybe thousands of fish, all the same species, swimming in the same direction, at the same speed, like a perfectly choreographed underwater dance. It’s a dazzling display of teamwork, a sight that leaves you wondering how they all manage to stay in sync.
Shoal of fish: A shoal of fish is a group of neighbors hanging out on the reef. These fish are casually socializing, different species sometimes even joining the party. They might not be moving in any particular direction, just spending time together (or maybe gossiping about that grumpy snapper).
The key difference between a shoal and a school of fish is coordination. Shoals are more relaxed gatherings, while schools of fish are all about synchronized movement. If a school of fish stops, they temporarily transform into a shoal.
Some fish are socio-holics, shoaling or schooling all the time, while others are more independent, joining the group only when needed.
While scientists can differentiate the terms shoal or school of fish, as regular divers, we can use the terms interchangeably. Don’t sweat it! As long as you can appreciate the amazing underwater spectacle, that’s all that matters.
Schooling fish is about survival and success, packed with benefits that keep these fishy friends thriving.
Predator avoidance: If a hungry shark approaches a lone fish – it is an easy lunch, right? But if the same shark is facing a shimmering school of hundreds, all moving in perfect unison. Suddenly, the shark’s not so sure. The sheer number of fish in a school confuses predators, making it a confusing, overwhelming buffet, making it nearly impossible for the predator to pick a single victim. These aggregations allow fish to effectively appear comparable to a large animal, which can discourage predators too.
Energy savings: Swimming alone in the vast ocean takes a lot of work. But fish in a school have a clever trick. By swimming close together, they take advantage of the water flow created by the fish in front of them, giving them a little extra push and letting them conserve precious energy. Studies show this fishy teamwork can save them up to 20% on swimming costs compared to going solo – that’s like getting the Dressel Divers online discount but for the school of fish!
Finding food: This is another challenge for a school of fish, but they have a weapon that the other predators don’t have – more eyes! With hundreds (or even thousands) of eyes scanning the water, a school can spot food sources way faster than a single fish ever could. Plus, everyone benefits from the discoveries of others. It’s all about cooperation. If one fish spots a patch of plankton or a hidden school of shrimp, the whole school can swoop in for a feeding frenzy!
Communication and interaction: Schools of fish aren’t just about survival, they’re also about community. Swimming together allows fish to interact and communicate. They can learn from each other, share info about hidden dangers or delicious food sources, and coordinate their movements for maximum efficiency.
Of course, the exact benefits of schooling can vary depending on the fish and the situation. But one thing’s for sure – swimming in a school of fish is a winning strategy for these underwater creatures.
Efficient reproduction:
Finding a mate can be tough, especially in the vast ocean. But for our fish in a school, it’s easy. Schooling behavior brings the sexes together, increasing the odds of successful reproduction for many fish species. Many fish species form spawning aggregations, which are schools consisting mainly of mature individuals that come together just for reproduction.
Have you ever wondered how a school of fish manages to swim in perfect synchrony? They move like a fluid unit, turning and changing shape without colliding, almost as if they had a choreographer, but they don’t.
Sight plays a crucial role. Most schooling fish have eyes on the sides of their heads, allowing them to constantly see their neighbors. Additionally, many species sport markings on the sides of their bodies that serve as reference points for the rest of the group to maintain formation.
But most importantly, according to scientists, is what they’ve dubbed “the lateral line.” It consists of a series of subdermal channels containing sensory receptors called neuromasts. The movement of water through the lateral line channels allows fish to detect vibrations and water movements, enabling them to react to water currents and orient their movements. When a fish in the school moves, it creates a pressure oscillation in the water, which is in turn picked up by the lateral line, allowing each fish to anticipate the movement of the rest of the school.
Most schools of fish lose their synchronization ability at night and cluster with less precision. This indicates that light is key to the coordinated movement of the fish school.
But, Who’s the leader? How do they all agree on where to go and what to do?
Decisions like changing direction to avoid a predator or finding a tasty patch of plankton seem to be made collectively.
Scientists believe schools of fish use a combination of factors to make decisions. Vision plays a big role. As fish in a school have eyes on the sides they constantly see their neighbors. If one fish spots danger or a food source, it might change direction, and the others will likely follow suit – kind of like a fishy game of underwater follow the leader.
There’s also evidence that fish might use a “quorum sensing” system based on the number of fish doing something. If enough fish in the school start swimming in a particular direction, others might follow the majority, even if it’s not the “safest” option.
Ok, we already know that a school of fish is a collection of marine animals that remain together, but this is not the only way to refer to them. The fact is that in the English language, we have different collective names for marine animals. Let’s know some of them.
A School of Barracudas Is Called a “Battery”
Watching a barracuda on a dive in the Caribbean Sea is normal. This is because they love to live near the coral reef and seagrasses. What is not so frequent is to see them in groups swimming together, and adults are usually quite solitary fish. However, they occasionally form groups for swimming and hunting. If you see one, you will know that this school of fish is called a “battery”.
A Group of Swordfish Is a “Flotilla”
When the school of fish is a group of swordfish, they are called “flotilla”. The word “flotilla” is a diminutive of the Spanish “flota” and means little naval fleet. It makes sense if we think in terms of the swordfish’s dorsal fin so similar to the sail of a vessel.
A School of Cod or a “Lap” of Cod
Although they are the kings of the North Sea, cod also have their collective name in English. Yes, a school of fish formed by gathering cod is a “lap”. One of the ways to fish for cod is with purse seine fishing. That is, to lap the net around the school of fish to catch it. Could this be the reason for this name?
A Group of Herring Is an “Army”
Herring are silver-colored fish that form large groups. We are not quite sure why this school of fish is called an “army”, although they move in unison like a battalion under the order Right Face, Fall out!”
Collective Names Based on the School of Fish’s Movements
According to PADI, there are some collective marine animal names related to the school of fish’s movement.
For example, a group of salmon is called a “run” of salmon. This name refers to the upstream movement of these fish. Dogfish move as a mass. This is why a school of these fish is called a “troop” of dogfish.
NAO researchers found the largest aggregation of eels ever recorded in the abyssal depths of the ocean. They named them a “swarm” of eels because they seemed to move with the collective intelligence of bees. Schools of eel are also called a “bed” of eel or “fry” of eel.
A Group of Sharks Is a Shiver
If there is a school of fish in which a scuba diver is interested, it is a “shiver” of sharks. Yes, that’s the name of a group of these marine animals. What do you think is the reason? Is it because of the emotion of seeing these stunning fish? Is it because of the undeserved bad reputation? Write your comment on Facebook, and share it with us.
We have considered some names for different schools of fish and marine animals, but there are many more: a bunch of sardines is a “family” meanwhile, a gathering of manta rays, spotted rays, or stingrays is a “fever.” You can find a “smack” of jellyfish, a “risk” of lobsters, and a “turmoil” of porpoises and on the sea beds, crabs meet up as a “cast” and “consortium.” Do you know another name for a school of fish?
