Kitsap Memorial Park, Poulsbo, WA – Today during a low tide exploration trip, our beach naturalist group happened upon a female Midshipman resting in the muck, blending into its mottled brown surroundings with ease. Our instructor gently picked her up and we all gasped as he turned her over.  Her body glowed metallic gold and bronze, as if she had been fashioned in a forge rather than a muddy beach. Rows of tiny dots formed silvery bead-like lines that followed the shape of her glistening body. What an unexpected contrast to the dull browns and olive greens of the muddy shore.

The interesting name “Midshipman” was first used due to the rows of light-emitting organs on the underside. These neat rows of organs look like brass buttons on a naval officer’s uniform, hence the descriptive name. Night-time divers can catch sight of the orderly rows of light, most likely used to attract prey, like small fish and crustaceans. But only the Midshipman know all the benefits of their special glow in the dark (bioluminescent) “buttons.”

Midshipman Female
Female Midshipman – Lines of Light Emitting Organs

Our golden female Midshipman will choose the nest where she will deposit all her eggs. Males have been busy selecting, preparing and defending perfect nesting sites by first excavating a kind of den under a rock. Then, they begin to sing… yes, sing, but not in the style of the latest pop singer. They will hum, grunt and growl loudly enough to be heard many yards away, especially if there are multiple nesting males on one beach.

The female just needs to choose which grunty song she likes the most, then reward the lucky crooner with her whole seasonal load of eggs. The male keeps up his singing and attracts additional females as each departs. This unusual arrangement continues as the lone male then stays with his booty of up to 1,300 eggs and aggressively guards them.  There are even “sneaker” males who try to steal into the nest along with the female to fertilize her eggs, then leave the singing male with the parenting duties.

Midshipman EggsIt is not uncommon to find one of these doting Midshipman fathers under a rock at low tide. Just remember, these guys have been through their paces and are tired, hungry and not in any mood to be bothered. They will remain in the nest until young larvae have hatched and begin to leave – approximately 45 days after fertilization. Take a quick look at them and their yellow eggs, then carefully replace the rock just as you found it.

As you track wonder, marvel at the interesting ways animal parents carry out their duties and listen for peculiar night time love songs, sung only on rocky shores.

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When and Where – Late spring and summer. Choose mudflat beaches at low tide to see and/or hear Midshipman. This well-camouflaged fish might just be sitting in sea lettuce waiting for the tide to rise again. Males can be found in shallow pools under rocks guarding pea sized yellow eggs clinging to the underside of the rock. Remember to only turn over rocks that are about the size of your head or smaller and be careful not to cut your hands on the sharp barnacles that cover rock surfaces.

Visit Discovery of Sound in the Sea to hear recordings of the humming, grunting and growling sounds made by Midshipman males. During mating season, midshipman stay buried in the sand during the day and come up at night to begin their vocalizations, so pay close attention to the sounds coming from mudflat areas after dark.

Wonder Triggers For Young Trackers  The best wonder triggers are those that occur naturally in the moment, but sometimes a few simple questions from an adult can trigger great observation and discovery.

  • Many times marine animals hide under rocks on the beach. Can you find a rock that is about the size of your head? Why do you think animals hide under the rocks?  What might they be hiding from? (predators, sun, wind, waves, etc.)
  • Study the rock before you help move it. Can you see anything moving around it? Do you see animals living on or near it? Try to remember where it is so we can put it back where we found it. (Barnacles are sharp so be very careful)
  • If you find a fish under the rock, describe what they look like. The Midshipman has a wide mouth and bulging eyes, kind of like a toad.  (They are also called Toadfish)
  • Can you find yellow eggs stuck to the underside of the rock? The fish under the rock is the father fish and is protecting the eggs. He will stay with them without even eating until they hatch.
  • Offer descriptive vocabulary to help children verbalize their observations – Is this fish smooth or rough/bumpy, light or dark colored, thick or thin, hairy or hairless?
  • Identify fish body parts – eyes, nose, mouth, fins, tail, gills, etc.

References and Resources

Discovery of Sound in the Sea – Listen to Midshipman Recordings

Bay Nature – Midshipman

Images – SPegany ©2018

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