Why do fish have strong memory?

Memory is key to survival. It helps animals find food, avoid danger, and recognize familiar places or other creatures. Fish live in wide, open waters filled with predators. With weak memory, they wouldn’t last a day.
Think about it logically:
How could fish species that have existed for over 500 million years continue to thrive, migrate, and reproduce without a robust memory system?

Scientific experiments reveal fish memory power

Here are several fascinating examples that clearly show fish have a surprisingly strong memory. Scientists have discovered many ways in which fish remember, learn, and adapt — proving they’re much smarter than most people think.

Spatial Memory Experiment

In a well-known study, researchers trained fish to identify where food was placed inside a tank at specific times of the day. Even after a two-week break, the fish gathered at the same place and time expecting food, showing that their memory lasted for weeks — not seconds.

The lever-pressing experiment

Another experiment introduced a lever that released food only at certain times. The fish learned to press it only when feeding time arrived, showing their ability to associate time, action, and reward — a sign of advanced cognitive function.

Fish that learn from mistakes sure hasn’t weak memory

A 2017 study on Guppy fish found that these fish can improve their performance in maze tests through repeated training. After four days, they completed the maze much faster than on day one — evidence of learning through memory similar to mammals.

Complex behavior: tool use and deception

Some fish species have been observed using tools to obtain food. For example, wrasses, especially the orange-dotted Tuskfish, have been observed using rocks as tools. It was dropping rocks on sea urchins to break their shells. Others, like Sailor fish, display protective strategies by attaching their eggs to plant leaves, allowing them to move them quickly if the nest is attacked. These behaviors demonstrate that fish are not mindless creatures but intelligent beings capable of planning and adapting.

Counting and numerical recognition for sure aren’t sign of a weak memory

Researchers showed fish cards with different numbers of dots. In over 1,200 tests, the fish chose the correct card 91% of the time. This shows they can compare numbers and remember patterns — skills once believed to belong only to higher animals.

Do manta rays remember their routes?

Manta rays may travel more than 2,000 km across the ocean — and they don’t do it by chance. These gentle giants remember their migration routes, food spots, and cleaning stations year after year. Scientists believe manta rays use both memory and environmental cues to navigate. It’s like they carry an invisible map in their minds, guiding them safely through the vast blue world.

Memory in aquaculture applications

Scientists have applied fish memory to sustainable aquaculture. By training fish to respond to feeding sounds, farmers can later release them into the sea and recall them during harvest using the same sound cue. This clever method proves that fish don’t have a weak memory at all — in fact, they can remember and react after weeks or even months. It also helps reduce feeding costs and supports environmentally friendly farming, all thanks to the strong and reliable memory of fish.

Fish can recognize faces, so no weak memory!

Studies have shown that archerfish can remember and recognize human faces — even after seeing dozens of them. Or, other interesting real-life story with a diver who once removed a fishing hook from a shark’s mouth. After that, the same shark started visiting her regularly — and even brought other sharks that also had hooks stuck in their mouths, as if asking for help. This shows that fish can recognize people, remember positive experiences, and even communicate them to others.

The myth about weak fish memory is entirely false

Scientific research proves that fish can remember things for weeks or even months. They learn from experience and show surprising intelligence. So next time someone says, “He has a fish memory!” — you can confidently correct them. And when you go snorkeling with Hurghada Today, take a closer look. The fish you meet might remember you longer than you think.

References
Oxford University research on Guppy fish behavior (2017).

Spatial memory studies in Animal Cognition journal.

Australian Marine Science Centre studies on fish learning.

How do whales and dolphins breathe?

Unlike fish, which extract oxygen from water using gills, whales and dolphins are marine mammals that breathe atmospheric oxygen through their lungs. They have a special opening on top of their heads called a blowhole, which functions like a nose. This allows them to inhale air and exhale carbon dioxide. During dives, the blowhole remains tightly closed by powerful muscles to prevent water from entering the respiratory system. When whales surface, they open the blowhole and release a strong burst of air and vapor before taking a deep breath and diving again. You’ve probably seen this famous fountain-like spout in photos before.

How long can they stay underwater?

Dolphins can typically hold their breath for 8–15 minutes, while large whales can stay submerged for up to 60 minutes. The record-holder, however, is the Cuvier’s beaked whale, which can dive for more than two hours and fifteen minutes in a single breath! This ability comes from their high concentrations of hemoglobin and myoglobin — two proteins that store oxygen in the blood and muscles — and their ability to slow their heart rate during deep dives to conserve oxygen.

If they breathe air, why do they die on land?

Whales and dolphins do not die immediately from suffocation when they are out of the water, because they breathe air through their blowholes, and technically, they can still inhale and exhale in open air. However, they do eventually die if they remain beached, but not primarily because they can’t breathe. The real causes include:

1. Crushing weight and internal pressure is deadly for whales and dolphins

A blue whale can weigh over 150 tons (150,000 kilograms). While in water, buoyancy supports its massive body weight. But once ashore, gravity exerts full pressure on its organs — especially the lungs and heart — causing them to collapse or stop functioning. Their skeletons are not designed to support such weight outside the water, leading to fatal internal injuries.

2. Overheating and thermal stress

Whales and dolphins have a thick layer of fat called blubber, which can be up to 30 centimeters thick and serves as insulation against cold ocean waters. However, this same insulation becomes dangerous on land, where there’s no water to cool their bodies. Their internal temperature rises rapidly, leading to thermal stress, tissue damage, and dehydration.

3. Dehydration and skin damage

Their skin is adapted to stay constantly moist. Once exposed to air, it begins to dry, crack, and lose moisture rapidly. This is why rescuers are often seen spraying water or covering whales with wet cloths — to keep them hydrated until they can return to the ocean.

4. Limited mobility and physical exhaustion

Whales and dolphins have streamlined bodies designed for efficient movement in water. On land, this adaptation becomes a hindrance; they cannot move or support themselves, causing muscle fatigue, compression injuries, and eventually death from exhaustion.

5. Starvation and energy depletion

These giants have enormous energy demands. A blue whale, for instance, consumes around 40 million krill per day — roughly 2–10% of its body weight. When stranded, they lose access to food and quickly run out of energy, leading to starvation.

Why do whales beach themselves in the first place?

Whale and dolphin strandings have been documented for centuries — with around 2,000 incidents recorded worldwide each year. Yet, the exact cause remains one of the great mysteries of marine biology. Some of the main theories include:

1. Illness or old age: Sick or elderly whales may deliberately isolate themselves and drift toward shore to die peacefully.

2. Geological disturbances: Underwater earthquakes or volcanic activity can disrupt their navigation systems.

3. Human interference and sonar noise: Naval sonar systems emit powerful sound waves that can disorient whales, causing them to flee in the wrong direction — often toward shallow waters. A famous example occurred in 2000 in the Bahamas, when 17 whales beached shortly after a U.S. Navy sonar test.

 What should be done when a whale is stranded?

When rescuers discover a stranded whale or dolphin, every second counts. They immediately begin keeping the animal’s skin moist, using buckets of seawater or wet cloths. Wet towels or blankets are gently placed over its body to prevent the skin from overheating or drying out. Next, rescuers adjust the animal’s position, easing the weight off its chest and fins to help it breathe more easily. Throughout the process, they have to stay calm and quiet — sudden noises can cause panic. Meanwhile, marine rescue authorities should be contacted to organize professional equipment and a safe return to the sea.

Now is clearer why whales and dolphins can’t live outside of water

Although whales and dolphins are air-breathing mammals, their bodies are precisely engineered for life in the ocean. Once on land, they face a deadly chain of effects — from internal pressure and overheating to dehydration and organ failure — that ultimately leads to their death within hours. Understanding this phenomenon is crucial not only for science but also for improving marine rescue and conservation efforts.

Distinctive Traits of the Crown-of-Thorns Starfish

This starfish is named for its venomous spines, which resemble a crown of thorns. It can grow up to 35 cm (14 inches) in diameter, with 16 to 23 arms. Like most dangerous species, it has stunning colors that range from red and purple to green and brown.

Habitat and Diet

Crown-of-thorns starfish prefer warm waters, so it lives in coral reefs throughout the Indo-Pacific region. They are common in the Great Barrier Reef, the Red Sea, and the tropical Pacific islands. We can find them at depths of 1 to 30 meters. This starfish feeds primarily on live coral polyps. It uses its stomach to digest coral externally, leaving behind bare, white skeletons. A single starfish can consume up to 10 square meters of coral in a year. They move slowly using their tube feet. While they don’t migrate long distances, they may disperse in search of food, especially during population outbreaks.

Reproductive Behavior and Mating Strategies of the Crown-of-Thorns Starfish

These starfish are prolific breeders. They spawn by releasing eggs and sperm into the water during specific seasons. A single female can produce millions of eggs in one spawning event. Fertilized eggs develop into larvae, which drift with currents before settling on the reef. Under certain conditions, crown-of-thorns populations explode. This often happens when water quality declines or predators are removed. During outbreaks, they can devastate coral reefs, eating large sections and causing long-term damage.

Interesting facts about this starfish

Here are some fascinating facts about the Crown-of-Thorns Starfish:

1. Like many other starfish, they can regenerate lost arms. If part of the central disc is attached, a single arm can grow into a new starfish.

2. During spawning, a single female Crown-of-Thorns starfish can release up to 60 million eggs in a single breeding season.

3. They are mainly active at night, using their tube feet to move across reefs.

4. Despite their defenses, they have natural predators, such as the giant triton snail, harlequin shrimp, and some species of fish.

5. Their spines has toxic substance, saponin, which deters many potential predators.

These starfish are a remarkable yet challenging species in marine ecosystems.

Should it be exterminated?

Managing crown-of-thorns outbreaks is crucial to the health of reefs. Efforts include manually removing starfish or injecting them with a solution that kills them. Protecting against predators and improving water quality also help control populations. However, despite their destructive nature, crown-of-thorns starfish play a role in reef ecosystems. By consuming dominant corals, they create space for other species to grow. This balance is crucial, as outbreaks can overwhelm reefs. Therefore, understanding and managing their impact is essential for the conservation of coral reefs worldwide.

Physical Features

Napoleon fish are large, reaching up to 2 meters (6.5 feet) in length and weighing over 180 kilograms (400 pounds). Their bright blue, green, and yellow outlines of scales make them stand out in all the planet’s oceans. They get their name from the prominent hump on their forehead. Juveniles are greenish with white spots, while adults turn vibrant shades of blue, green, and purple. Males are usually brighter in color than females. Intricate blue and green lines radiate around the eyes, giving the fish an exotic and striking appearance. Males are larger than females and develop a prominent hump on their forehead as they age.

Habitat of the Napoleon fish

These fishes live in coral reefs throughout the Indo-Pacific region. They are commonly found in the Red Sea, Indian Ocean, and parts of the Pacific Ocean. Popular locations include the Great Barrier Reef, the Maldives, and Palau. They prefer warm, clear water and are usually seen at depths between 1 and 100 meters. They use coral crevices and caves as shelter because they offer protection from predators. The fish primarily feed on mollusks, crustaceans, echinoderms, and smaller reef fish. That’s why we often encounter them snorkeling around Gifton Island during visits to the island’s beaches. They are one of the few predators that can eat toxic species like crown-of-thorns starfish and boxfish. Their strong jaws and thick lips allow them to crush hard shells with ease.

Behavior and Migration

Napoleon fishes are solitary creatures, although young may form small groups. Adults are territorial and often patrol their territory. They are not long-distance migrants but may move within their home range to find food or mates. Active during the day, they spend the nights hiding among coral structures.

Mating and Reproduction of Napoleon Fish

These fishes are protogynous hermaphrodites, meaning they start life as females and can change into males later. This change happens when they reach a certain size and social status. Spawning occurs in groups at specific sites during certain times of the year. Females release eggs into the water, which males then fertilize. The fertilized eggs drift with currents until they hatch.

Conservation Status

Napoleon fish is listed as endangered by the IUCN. Overfishing and habitat loss are threatening their populations. They are highly sought after for their meat and are often caught illegally. Marine protected areas and sustainable practices are essential for their survival. Napoleon fishes also play a vital role in maintaining the health of reefs. By eating harmful species such as the thorny starfish, they prevent damage to corals. Their protection ensures a balanced marine ecosystem.

Why you need Hurghada Today to meet Napoleon Fish in the sea?

The Napoleon fish is not only a key species for the health of coral reefs, but also an emblem of marine biodiversity. It is a symbol of the beauty and diversity of the ocean. With our dedicated guides, you will have the opportunity to see them while diving or snorkeling along the coast of Hurghada. The preservation of its habitat is essential for its survival, and we wholeheartedly support this by protecting the reefs and the purity of the sea.