Muscular system of a fish [Fishy Matters - Episode 11]

Summary

In this episode, we dive into the fascinating muscular system of fish. The majority of a fish's body mass consists of large muscles in the body and tail, divided into two types: white and red muscles. White muscle is used for short bursts of swimming and lacks oxygen-carrying pigments, while red muscle supports sustained swimming, rich in oxygen-binding pigments like myoglobin. The distribution of muscle types varies among species, with migratory fish having a higher proportion of red muscle. Understanding these differences helps explain fish behavior and energy use during swimming.

Takeaways

• 😀 Fish muscle structure consists of large muscles in the body and tail, making up the majority of the fish's body weight.
• 😀 Myotomes (muscle segments) are arranged vertically along the fish's body and are separated by connective tissue called myocameta.
• 😀 White muscle makes up about 90% of most fish muscles and is essential for short bursts of swimming, especially in sluggish swimmers.
• 😀 White muscle fibers lack pigmentation, have a poor blood supply, and rely on anaerobic pathways (glycogen to lactate) for energy.
• 😀 Red muscle makes up about 10% of fish muscle and is crucial for continuous, sustained swimming, found in active swimmers like tuna and mackerels.
• 😀 Red muscle is rich in capillaries, hemoglobin, and myoglobin, allowing it to efficiently use oxygen for energy production during long-distance swimming.
• 😀 Myocameta, the connective tissue in fish muscle, contains collagen, which softens and gelatinizes quickly when cooked.
• 😀 The collagen in fish muscle breaks down at lower temperatures compared to beef, making fish meat more tender and quick to cook.
• 😀 Fish muscle is divided into apaxial (above the horizontal septum) and hypaxial (below the horizontal septum) muscles, contributing to its movement.
• 😀 The myotomes on the left and right halves of the body are separated by a vertical septum, with a horizontal septum dividing the upper and lower muscle masses.
• 😀 Fish species vary in muscle composition, with migratory species like marlins and tunas having a higher percentage of red muscle for long-duration swimming.

Q & A

What is the primary component of a fish's body mass?

The large muscles of the body and tail comprise the majority of the body weight in most fish.

What are myotomes in fish muscle structure?

Myotomes, also known as myomeres, are vertically divided sections of muscle that run along the length of a fish's body. They are separated by connective tissue called myocameta.

How does the muscle fiber structure in fish differ from that of mammals?

Fish muscle fibers are typically long and narrow, reaching up to 3 cm in length and 10-100 micrometers in diameter, while mammalian muscle fibers can vary significantly in structure and size.

What is the function of the white muscle in fish?

White muscle, which makes up about 90% of most fish muscle mass, is used for short bursts of swimming. It functions anaerobically, converting glycogen into lactate for energy.

Why is red muscle important for certain fish species?

Red muscle is essential for sustained, continuous swimming as it is rich in oxygen-carrying pigments like myoglobin and has a high capillary density to support aerobic respiration.

What distinguishes red muscle from white muscle in fish?

Red muscle fibers are thinner and have a higher concentration of myoglobin, which gives them a red color, while white muscle fibers are thicker and lack these pigments.

What are some examples of fish that rely mostly on their white muscles?

Fish such as groupers and snappers, which are sluggish swimmers, predominantly use their white muscle for short bursts of activity.

How do red muscles support the movement of migratory fish?

Red muscles in migratory fish like tuna and mackerel are highly developed and enable them to maintain high levels of continuous swimming over long distances due to their superior oxygen supply.

What is the role of myocameta in fish muscle?

Myocameta are sheets of connective tissue that separate muscle cells in the fish's body, providing structural support and allowing the muscle fibers to function effectively.

Why do fish muscles soften faster than those of red meat during cooking?

Fish muscle contains less collagen than red meat, and its collagen breaks down at lower temperatures (around 45°C), causing the muscle to soften and gelatinize faster when cooked.