Porichthys notatus facts for kids
Quick facts for kids Porichthys notatus |
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The Plainfin Midshipman (Porichthys notatus) is a type of toadfish. It belongs to a group of fish called "midshipmen." You can find this fish in the eastern Pacific Ocean. Its home stretches along the coast from Sitka, Alaska, all the way down to Magdalena Bay in Baja California Sur.
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About the Plainfin Midshipman
This fish can grow up to 38 centimeters (about 15 inches) long. Its back is usually brownish, olive green, or even a shiny purple. Its sides are lighter, and its belly is yellowish or golden. It has a white spot and a black crescent shape just below its eye. Young fish might have a dark saddle-like mark on their back. The Plainfin Midshipman has wide pectoral fins (like arms) and a narrow, rounded tail fin.
Where They Live and What They Do
Most of the time, these marine fish live on sandy or muddy ocean bottoms. They can be found in shallow waters near the shore or in deeper areas, up to 366 meters (about 1,200 feet) deep.
The Plainfin Midshipman is a nocturnal animal. This means it feeds at night and rests during the day. When it rests, it often buries itself in the sand to stay hidden. Its diet includes small crustaceans, like crabs and shrimp, and other fish.
Reproduction and Life Cycle
Plainfin Midshipmen lay eggs, which is called being oviparous. The male fish come in two types: Type I and Type II.
The Type I male is bigger and finds a good spot for a nest. This is usually under a rock in the intertidal zone, which is the area between high and low tide. After a female lays her eggs in the nest, she leaves. One female can lay up to 400 eggs, and larger females lay more. A Type I male might mate with several females. He can end up with over 1,000 eggs in his nest!
The eggs and tiny larvae (baby fish) stick to the nest wall. The male takes care of them by fanning them with his fins. This keeps the eggs clean and makes sure they get enough oxygen. If the tide goes out, he also keeps them wet so they don't dry out. He protects the young fish until they are big enough to leave the nest, which is about 45 days after the eggs were fertilized.
The Type II male is much smaller than the Type I male. There are also far fewer Type II males. Unlike Type I males, Type II males do not build or guard nests. Instead, they sneak into the nests of Type I males and fertilize the eggs there.
Sometimes, a male fish tending his nest can get stuck when the tide goes out. He might even be completely out of the water. But this fish is very tough! It can breathe air and is well-suited to low oxygen and high carbon dioxide levels.
Bioluminescence: The Fish That Glows!
The Plainfin Midshipman can actually glow in the dark! It has special light-producing organs called photophores. These are tiny spots on its head and body, with over 700 on one fish. Each one is about a millimeter wide.
These photophores contain a chemical called luciferin. When another chemical, Norepinephrine, activates them, they produce a bright green glow. The fish usually glows during courtship, which is when they are trying to find a mate. The glow might also help them hide from predators. Young fish have photophores that point downwards. This helps them blend in with the light from above, making it harder for predators to see their silhouette.
Not all Plainfin Midshipmen glow. There are two main groups of this species. The southern group, found as far north as San Francisco Bay, can glow. But most fish from the northern group, especially those from Puget Sound, do not. The non-glowing fish don't have luciferin in their photophores.
Scientists found that if they give luciferin to non-glowing fish, they start to glow! This luciferin came from a glowing ostracod (a tiny crustacean) called Vargula hilgendorfii. It is believed that glowing Plainfin Midshipmen get their luciferin by eating these types of glowing crustaceans. The northern fish likely don't glow because they don't have these special crustaceans to eat.
Vocalization: The Humming Fish
Both male and female Plainfin Midshipmen can make sounds. Females might make a short grunting sound, usually when they are fighting. Type II males do similar grunts.
The Type I male is much more vocal. He makes long strings of grunts and growls when fighting. But his courtship call is a long, deep hum. He can make this humming sound for over an hour at a time! The sound can reach frequencies near 100 Hz. When a male hums, females that are ready to lay eggs will swim towards him.
The fish makes these sounds using special muscles around its swim bladder. It hears the sounds with an organ in its inner ear called the saccule. During breeding season, the female's saccule changes. This helps her hear the male's calls even better.
People in some areas know this fish well because of its sound. Where many males are breeding, you can clearly hear their loud, humming calls from underwater, even on land! In parts of Washington and the San Francisco Bay Area, these noisy fish are common.
The fish is famous in Sausalito, California, where many people live on houseboats. During breeding season, the fish hum so loudly at night that they keep the houseboat residents awake! Their loudest calling is between midnight and 6:00 a.m. Even though they can be annoying, the fish inspired a special event in Sausalito: the Humming Toadfish Festival.
People have described the sound of the fish's calls in many ways. Some say it sounds like a chorus of kazoos, or B-29 planes flying. Others compare it to an amplifier, a didgeridoo, "a drone of bees," or "an orchestra full of mournful, rasping oboes."
Predators and Other Organisms
The Plainfin Midshipman is an important food source for other animals. For example, it is a common meal for the bald eagle in some coastal areas. One study on Vancouver Island found it was the most common food bald eagles fed to their babies. However, this is a concern because these fish can have high levels of pollutants, like dioxin.
Other animals that eat the Plainfin Midshipman include the northwestern crow, the glaucous-winged gull, and the great blue heron. Seals and sea lions also enjoy eating them.
This fish can also be home to tiny creatures called parasitic copepods. Two types found on the Plainfin Midshipman are Lepeophtheirus remiopsis and Hamaticolax prolixus.
Conservation Status
The Plainfin Midshipman is not a threatened species. It is found in many places and its numbers seem to be stable.
Images for kids
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Drawing showing the glowing organs and lateral line on a Plainfin Midshipman.
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Western gulls and other birds will catch and eat plainfin midshipman.
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