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Prowfish

life science Maturity 5-7 Next article →

The prowfish, known scientifically as Zaprora silenus, is a unique marine fish. It lives in the northern Pacific Ocean. This species is very special because it is the only living member of its family, Zaproridae.

Prowfish (Zaprora silenus)
Prowfish (Zaprora silenus)

While the prowfish survives today, its relatives did not. Scientists have found fossils of extinct species from the past. One species, †Zaprora koreana, was found in South Korea. It lived in the Middle Miocene Duho Formation. Another genus, †Araeosteus rothi, was found in California. These fossils were located in the Monterey and Modelo Formations. These discoveries help us understand the history of this fish family.

The physical body of an adult prowfish is quite distinct. They have stout, elongated bodies that are laterally compressed. This means their bodies are flattened from side to side.

Prowfish (Zaprora silenus)
Prowfish (Zaprora silenus)

They possess a single, high dorsal fin. This fin runs almost the entire length of their back. The dorsal fin contains between 54 and 58 pliable spines. They also have an extensive anal fin and a large, rounded tail fin. Their pectoral fins are enlarged to help them move. Interestingly, they are missing pelvic fins entirely. Their head is convex and ends in a projecting snout. This shape is why the family is named Zaproridae. The name comes from the Greek words "za," meaning an intensifier, and "prora," meaning "prow." A prow is the front part of a ship.

prowfish juvenile
prowfish juvenile

Prowfish have several specialized features for living in the ocean. Their mouth is slightly upturned. Inside the jaws, they have small, sharp, and closely set teeth. The head also features sensory pores. These pores are easy to see because they have fringes of blue or white. Their skin is covered in small ctenoid scales. The color of a prowfish can vary. They are typically bluish-grey or olive brown with small dark spots. Their underside is usually a lighter shade. One unusual fact is that they lack a lateral line and a swim bladder. A swim bladder is an organ many fish use to control their depth.

Prowfish (Zaprora silenus)
Prowfish (Zaprora silenus)

The lifestyle of a prowfish changes as it grows. Most adults are benthic animals. This means they spend their time on or near the ocean floor. They prefer rocky substrates and live in waters ranging from shallow areas to deeper depths. However, juvenile prowfish are pelagic. This means they live in the middle levels of the water column. Young fish feed exclusively on jellyfish. They even seek shelter inside the bells of larger jellyfish to stay safe. This behavior is so specific that they are sometimes confused with medusafish. As they grow, they transition from the open water to the rocky bottom.

prowfish juvenile
prowfish juvenile

Diet plays a major role in how a prowfish lives. Adults use their large mouths to tear chunks of food from scyphozoans and salps. These are types of jellyfish and soft-bodied sea creatures. Adults may also eat amphipods or smaller fish. Because they live near the bottom, they are part of a complex food web. Larger predators, such as Pacific halibut and skates, hunt the prowfish. The fish must balance finding food with avoiding these larger hunters. Their ability to eat jellyfish allows them to thrive in specific parts of the Pacific.

Prowfish (Zaprora silenus)
Prowfish (Zaprora silenus)

We know a few specific details about the life cycle of the prowfish. Most female prowfish reach maturity when they are about five years old. There is very little sexual dimorphism in this species. Sexual dimorphism is when males and females look different from each other. In the case of the prowfish, females are simply slightly heavier than males for their length. While much is known about their bodies, scientists still know very little about how they reproduce. This remains a mystery for researchers studying the species.

prowfish juvenile
prowfish juvenile

The prowfish is important for more than just science. In many remote regions, they are vital to subsistence fisheries. This means local people rely on catching them for their daily food supply. Their range is vast across the northern Pacific. They stretch from the Aleutian Islands in Alaska west to Kamchatka, Russia. They also live from the Navarin Canyon in the Bering Sea south to Hokkaidō, Japan. They can even be found as far south as Monterey, California. Understanding these fish helps us understand the health of the entire Pacific ecosystem.

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File:Prowfish (Zaprora silenus).jpg
Prowfish (Zaprora silenus).jpg
File:prowfish juvenile.jpg
prowfish juvenile.jpg
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