Lepidophagy

Key takeaways

Lepidophagy belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Lepidophagy to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Lepidophagy from memory before moving on to harder problems.

Reference excerpt

Lepidophagy is a specialised feeding behaviour in fish that involves eating the scales of other fish. Lepidophagy is widespread, having evolved independently in at least five freshwater families and seven marine families. A related feeding behavior among fish is pterygophagy: feeding on the fins of other fish.

Species

Lepidophagy, or scale-eating, has been reported in a range of fish, including Chanda nama (family Ambassidae), Plagiotremus (family Blenniidae), Terapon jarbua (family Terapontidae), a few Ariopsis and Neoarius species (family Ariidae), Pachypterus khavalchor (family contentious - variably in Schilbeidae, Bagridae, or Horabagridae), Macrorhamphoides uradoi (family Triacanthodidae), several pencil catfish (family Trichomycteridae), some piranha, Exodon paradoxus, Probolodus, Roeboides and Roeboexodon species (order Characiformes), Cyprinodon desquamator (family Cyprinodontidae), along with all six Perissodus species, Xenochromis, Haplochromis welcommei, Docimodus, Corematodus and Genyochromis mento (family Cichlidae from the African Great Lakes). Several of these scale-eaters also feed on fins of other fish, and many omnivorous or predatory fish may on occasion nip the fins of other fish. Only a few species are specialized fin-eaters, or pterygophagous; these include Belonophago, Eugnathichthys and Phago (family Distichodontidae), Aspidontus (family Blenniidae), and Smilosicyopus (family Gobiidae). A somewhat related behavior is found in Magosternarchus, which feed on the tails (both fin and connective tissue) of other gymnotiform knifefish.

Physiology Many species of cichlid fish have evolved specialized teeth and mouth structures that make them better able to feed on the scales of other fish. Other species of fish also have a morphology that is better adapted to scale-eating. Many such species' oral structures closely resemble each other even though they live in different habitats, and many also have specialized jaw structures. One species of fish in particular, called Roeboides prognathous, has a jaw structure that is extremely specialized for lepidophagy. Certain species of lepidophagous catfish, Pachypterus khavalchor, have digestive enzymes which help them to more readily break down the fins, eyes, scales of other fish. There are other morphological structures that are important in scale-eating habitats. There are six lepidophagous cichlid species who employ mimicry strategies to deceive their prey: the colors of the cichlid fish closely resemble the colors of some of their prey. However, they not only eat the scales of the fish they resemble, but also prey on a wide range of other species.

Behaviour

There are many different behaviours associated within lepidophagous fish. Aggression and attack behaviours like chasing and striking prey are common among Pachypterus khavalchor catfish, who then eat the fallen scales of their prey. The attack behaviour of the wimple piranha Catoprion mento, whose diet consists mainly of scales, is described as a "high-speed" attack. They ram into their prey with their mouth open, biting the prey to obtain their scales. Perissodus microlepis cichlid fish tear off the scales of their prey as they swim past. This is very different from other lepidophagous species, who merely knock the scales loose by striking the prey. There are differences and similarities in lepidophagous behaviours across species. For example, the siluroid catfish's attacking behaviour is similar to that of the Probolodus heterostomus: they both follow their prey and attack their prey from behind. This is different from the behaviour of Roeboides prognatus and Exodon paradoxus, who remove scales more easily by attacking a specific part of their prey's body called the caudal area. Many studies have examined the hunting behaviours of scale-eating fish and how those behaviours have evolved over time. Certain species of cichlid aggressively mimic the behaviours of their prey, a tactic rarely used by other scale-eating fish species.

Niche The differences in the niche of certain species may play a role in their behaviours. Lepidophagous behaviours only exist in some species. Adaptive radiation has been mentioned in many articles as having a role in the evolution of lepidophagy. There is some evidence to support this but much is also unclear. Some behaviours in certain species of fish support the theory that extreme environments could be potential causes of scale eating behaviours. Some of those species are named below.

Cyprinodon pupfish

In the case of Cyprinodon pupfish, almost all have a diet of algae and detritus, but the species Cyprinodon desquamator (only scientifically described in 2013; previously known as Cyprinodon sp. "lepidophage" or Cyprinodon sp. "scale-eater") is different. There are only two known cases where several Cyprinodon species live together: lakes in San Salvador Island, the Bahamas, and Lake Chichancanab, Mexico. In both cases, the co-occurring Cyprinodon species have diverged into feeding on different things and in lakes on San Salvador Island; this includes the scale-eating C. desquamator (there are no scale-eaters in Lake Chichancanab, although C. maya has become a fish-eater).

Cichlids

There is a diverse range of cichilds in Lake Tanganyika in East Africa but the Tanganyikan cichlid tribes, Perissodini and Plecodus, feed on the scales of cichlids and other fishes. The species of cichilds that exhibit scale eating behaviours live in deep water with very low levels of oxygen and have had to rapidly evolve to keep up with a changing environment and lack of food.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Lepidophagy

Start with the simplest possible case. Write down what Lepidophagy claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Lepidophagy before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Lepidophagy ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Lepidophagy

In research: Lepidophagy appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Lepidophagy in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Lepidophagy is common in secondary-school and first-year university syllabi. It links to neighbouring topics Ambassidae, Ariidae, Carnivory, so understanding it makes those chapters shorter.
In everyday life: Look for Lepidophagy outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Lepidophagy in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Lepidophagy means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Lepidophagy out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lepidophagy in simple terms?

Lepidophagy is a specialised feeding behaviour in fish that involves eating the scales of other fish. Lepidophagy is widespread, having evolved independently in at least five freshwater families and seven marine families.

Why does Lepidophagy matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Lepidophagy?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Lepidophagy.