Amanda Dice: Using Light for Survival, September 13, 2017


NOAA Teacher at Sea

Amanda Dice

Aboard Oscar Dyson

August 21 – September 2, 2017

 

Mission: Juvenile Pollock Fishery Survey

Geographic area of cruise: Western Gulf of Alaska

Date: September 13, 2017

Weather Data: Rainy, 76 F

Baltimore, MD

Science and Technology Log

Now that I am back home, I have some time to think about the variety of animals I saw on the cruise and do a little more research about them. Many of the animals we caught in our net have the ability to light up. This adaptation is known as bioluminescence. Different species use bioluminescence in different ways to help them survive.

 

Myctophids are a type of fish also known as a lantern fish. These small fish can occupy the same habitat as juvenile pollock, and we caught several of them at our sampling stations. I got a chance to look at them closely and I could see small spots, called photophores, along the sides of their bodies. In dark waters, these spots have bioluminescent properties. Lantern fish can control when to light them up and how bright the spots will glow.

 

There are many different species of lantern fish. Scientists have learned that each species has a unique pattern of bioluminescent photophores along the sides of their bodies. For this reason, it is believed that lantern fish use their bioluminescent properties to help them find a mate.

myctophid

The photophores can be seen as white spots on this lantern fish. Image courtesy of NOAA.

Lantern fish also have bioluminescent areas on the underside of their bodies. This adaptation helps them achieve what is known as counter-illumination. In the ocean, a predator can be lurking in the dark waters below its prey. Since many things feed on lantern fish, it is important for them to have a way to camouflage into the environment. When a predator looks up, during the day, a fish that is lit up on the bottom will blend in with the lighter waters above it, making it hard to see.

counterillumination 2

The camouflaging effect of counter-illumination can be seen when this bioluminescent fish lights up its underside. Image courtesy of the Smithsonian.

Lots of animals use this technique to help them hide from predators, including squid. We pulled in many small squid in with our samples that had patterns of photophores on them. Depending on the species, squid also use bioluminescence to attract mates and to confuse predators.

squid NOAA 2

The pattern of lighted photophores can be seen on this squid. Image courtesy of NOAA.

In addition to fish and crustaceans, we also pulled in a variety of jellyfish. Jellyfish also have bioluminescence characteristics. Many jellyfish use light as a way to protect themselves from predators. When a jellyfish is threatened by a predator, it flashes in a rapid pattern. This signals other fish nearby that it is being hunted. This can alert larger predators, who may be hunting the predator of the jellyfish. The larger predator will then swoop in after the jellyfish’s predator, allowing the jellyfish to escape!

Jellyfish NOAA

Many jellyfish use bioluminescence to protect themselves from predators. Image courtesy of NOAA.

Personal log

I have been home for over a week and I think I finally have my land legs back again. Looking back on the experience, there were so many little surprises that came with living onboard a ship. One thing I noticed is that I got much better at walking around the longer I was there. I learned to always have one hand available to grab a railing or brace myself during any sudden movements. However, I never quite mastered getting a decent workout in on the treadmill! Another surprise is how relaxing the rocking of the ship could be when I laid down. I thought the movement would be distracting, but it actually helped me drift off to sleep!

Did you know?

There are many superstitions surrounding life on a ship. It is considered bad luck to have bananas on board and whistling is discouraged. Whistling onboard a ship is thought to bring on wind and storms!

 

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