The beautiful Hidden Language of fish use an astonishing array of signals to share information. We humans often equate communication with spoken words and vocalizations. But beneath the surface of the ocean lies a world teeming with life that challenges this assumption. Far from being “mute as a fish,” many marine creatures—especially fish—have rich, diverse, and essential ways to communicate for survival.
Marine Species live in an environment like the underwater realms of Anilao, where sound travels faster and farther than in air, and where visibility is often limited like in the deep waters of Subic Bay. As a result, the Hidden Language of Marine Species has evolved in remarkable ways. They use sound, body language, color changes, chemical signals, and even electrical impulses to interact with one another. Whether they are attracting mates, warning of predators, coordinating group movements, or asserting dominance, fish engage in constant dialogue—just in ways humans are only beginning to understand.
Here’s a deeper look into the hidden language of fish:
1. Acoustic Communication Language of Marine Species (Sound):
The Underwater Symphony
Sound travels much faster and farther in water than in air, making it an ideal medium for long-distance communication in the aquatic realm. Fish lack vocal cords so they instead produce a surprising variety of sounds, often inaudible to the human ear,
Swim Bladder Vibrations
Several fish species are known or strongly suspected to use specialized sonic muscles to produce sounds by vibrating their swim bladders. These sounds—grunts, purrs, pops, and knocks—serve purposes like territory defense, warning signals and mating. Like the yellow damsel fish. They generate “pops” and “chirps” using fast-twitch sonic muscles. These vibrations are transmitted through the swim bladder.These sounds are especially frequent during aggressive interactions to defend a territory or establish a social hierarchy.
This demonstrates that many reef fish in the Philippines are far from silent. By using internal sonic mechanisms, they send complex signals to one another—revealing a rich, often overlooked layer of life beneath the waves.
Stridulation
Several reef fish in the Philippines generate sound by rubbing together hard body parts—a process known as stridulation. This can involve grinding teeth, rubbing fin spines, or scraping bones. These sounds are typically used for aggression, defense, or communication within species. For example the Brown Tang common in Anilao shores has been observed making slight stridulatory sounds under duress.
Stridulation in tangs usually involves rubbing the base of their pectoral fins against bony structures in the shoulder girdle or grinding their pharyngeal (throat) teeth. This produces clicking or rasping sounds, often when the fish is handled, threatened, or fighting with other fish.
Stridulation is not a universal trait even within a fish family. The presence or absence of stridulation depends on both anatomy and behavior. If a species does not have the specific skeletal-muscular adaptations, it won’t produce these types of sounds.
Purpose of Sounds:
Territorial Displays: Sounds can be used to warn rivals away from a defended territory.
Alarm Calls: Some species emit warning sounds to alert conspecifics to the presence of predators.
Social Cohesion: Sounds can help maintain school structure and facilitate social aggregation.
Courtship and Spawning: Male fish often produce specific calls to attract mates and signal their readiness to spawn.
2. Chemical Communication A Language of Marine Species (Pheromones):
The Scent of Information
Fish possess a highly developed sense of smell, making chemical signals, or pheromones, a crucial mode of communication, especially in environments with poor visibility. These chemical cues are released into the water and detected by specialized receptors:
Nemo is the most notable examples of reef fish that use chemical cues or pheromones to communicate. Clownfish are well-studied for using pheromones to maintain social hierarchy within a group. The dominant female emits chemical signals that suppress sex change in subordinates. Maintaining strict female-dominant hierarchies in the anemone, ensuring only one breeding pair exists. Similar species characteristics are the Damselfish who are known to release alarm pheromones when injured, which serve to alert nearby fish of a predator’s presence—triggering evasive behavior and enhancing the chances of group survival.
Another fascinating example of chemical communication can be found in the shrimp gobies that inhabit the sandy bottoms of Calatagan. These gobies form a mutualistic relationship with burrow-digging pistol shrimp, and their coordination relies heavily on chemical cues. The shrimp, which has poor vision, depends on the goby’s warning signals—both tactile and chemical—to avoid danger, while the goby benefits from the safety of the shrimp’s burrow.Much like the anemonefish and their host anemones, this partnership showcases how reef and sand-flat species use pheromones and chemical communication to survive and thrive in the underwater world.
Many fish also use chemical cues to find their home reef or recognize kin. For example, sharks may use olfactory cues to locate the reef where they were born. Some cichlids use scent to identify their offspring. While sharks use pheromones, mostly in mating and possibly social grouping. They have a legendary sense of smell that plays a key role in detecting these pheromones over great distances.
Pheromone Functions:
Sexual Selection and Reproduction: Pheromones play a vital role in attracting mates, indicating reproductive readiness, and synchronizing the release of eggs and milt for successful external fertilization.
Alarm Signals: When injured, some fish release “alarm substances” (Schreckstoff) from their damaged skin, prompting avoidance behavior in other fish of the same or related species.
Species and Individual Recognition: Pheromones can help fish identify members of their own species, their sex, and even individual identities, including their position in a dominance hierarchy.
Schooling and Navigation: Chemical signals can aid in maintaining school cohesion and may even play a role in “homing” for anadromous fish returning to their birth streams.
3. Visual Communication: A Language of fish
Colors, Patterns, and Dances
While limited in deep or murky waters, visual signals are highly important in well-lit environments like coral reefs:
Predator Deterrence: Flashing lights might startle or confuse predators.
Color Changes: Many fish can rapidly alter their skin coloration, brightening or darkening to convey messages about:
Mood and Health: Changes in color can indicate stress, illness, or excitement.
Courtship Displays: Vibrant colors are often used to attract mates.
Warning Signals: Bright, contrasting colors can serve as aposematic (warning) signals to deter predators (e.g., lionfish).
Camouflage and Mimicry: Some fish change color to blend in with their surroundings or to mimic other species.
Body Postures and Movements: Fish use a “silent dance” of specific movements to communicate:
Fin Displays: Erect fins can signal aggression or territorial claims, while relaxed fins might indicate contentment.
Swimming Patterns: Specific swimming patterns can guide other fish to food sources or indicate escape routes.
Body Posturing: Different postures can establish dominance or show submission.
Bioluminescence: In the deep, dark ocean, some fish produce their own light through chemical reactions (bioluminescence). This light can be used for:
Species Recognition: Unique light patterns help fish identify others of their kind.
Attracting Mates: Specific light displays can draw in potential partners.
4. Electrical Communication: A Language of fish
A Shocking Conversation
Certain fish species have evolved specialized electric organs to generate and detect electrical fields. This highly specialized form of communication is particularly useful in dark or turbid waters:
Hunting and Defense: Strong electrical discharges can be used to stun prey or deter predators.
Electric Organ Discharge (EOD): Weakly electric fish produce continuous electrical discharges with specific frequencies and waveforms.
Functions of Electrical Signals:
Navigation: Electric fields help fish “sense” their surroundings in the dark, much like radar.
Finding Mates: Specific EOD patterns can attract potential partners.
Identifying Rivals: Differences in electrical signals can help fish distinguish competitors.