The New Year’s Eve fireworks may be behind us but, believe it or not, fabulous fireworks displays play out in dark ocean waters around the world every day. According to NOAA Senior Scientist and Deep Sea Researcher Dr. Edie Widder, “Bioluminescence in the ocean is the rule rather than the exception.”
First things first: what’s bioluminescence? It’s the production of light from a chemical reaction inside an organism, produced by animals for defense, attracting mates or finding food. Numerous deep sea creatures exhibit bioluminescence and more than a few light-producing organisms are found right here in Puget Sound—some of which are even housed at Seattle Aquarium.
Bioluminescence is sometimes confused with other forms of light:
- Fluorescence—When particular wavelengths excite a material, i.e. black light or the green fluorescent protein (GFP) in the Aequorea Victoria jellyfish.
- Phosphorescence—Similar to fluorescence, where a material is excited but has a longer-lasting effect, i.e. glow-in-the-dark stickers or many species of coral.
- Iridescence—When light is separated into component wavelengths and we see distinct colors in close sheens, i.e. soap bubbles, beetles, abalone shells.
Evolution of fish bioluminescence
According to a study conducted in 2016, fish evolved to make their own light at least 27 separate times. Bioluminescence is likely a much more common phenomenon than most people would think. It is found in over 700 genera of organisms; eighty percent of these occur in the ocean.
This study looked just at ray-finned fishes and not at other types of bioluminescent organisms. In these fishes, bioluminescence can be intrinsically generated (produced by a chemical process within the fish’s own body) or generated through bacterial symbiosis (bioluminescent bacteria are housed within the fish’s body).
Intrinsic bioluminescence evolved eight separate times throughout history, with more than half of known bioluminescent fish species utilizing this method of producing light. Of the 1510 known bioluminescent ray-finned fishes, about 785 produce their own light, though it is unknown how most of them obtain the necessary components for the chemical reaction (in at least some species it appears to be through their diet). Bacterially aided bioluminescence evolved at least 17 separate times.
Bioluminescence in human history
Bioluminescence holds a special fascination for many people. Imagine being able to produce your own light—it sounds like some kind of superpower! And yet it’s remarkably common among many animals, especially in the deep ocean. Although humans are not capable of bioluminescence, we have found opportunities throughout history to appreciate and utilize this ability in other creatures.
For example, Aristotle wrote about bioluminescence in his work De Anima in 350 B.C. During World War Two, Japanese soldiers used dried ostracods, a type of bioluminescent plankton, as a source of light. In 1954, James Lovell followed a bioluminescent wake to land his fighter plane on an aircraft carrier after his instruments failed during a night flight. And today, we have toys that allow anyone to capture the wonder of bioluminescence.
Everyone loves a good year-end wrap-up, and we at the Seattle Aquarium are no exception. Here are a few of our favorite highlights from 2016, and happy 2017 to all!
Rialto rescue and rehab
Stranded sea otter pup Rialto came to the Seattle Aquarium in August for rehabilitation with a 20 percent chance of survival. Under the care of numerous staff and volunteers here, Rialto transformed from dangerously sick pup into a healthy, curious young otter.
Full-steam-ahead seawall construction
Despite a second year of construction at our front door, our attendance increased in 2016 and we’re on target to welcome over 800,000 visitors by year-end. We hope one of them will be you!
Tucker the sea turtle came to us for rehabilitation after being stranded on a beach in Oregon. With a serious case of pneumonia, his chances of survival were not considered to be very high. However, he beat the odds and made a fantastic recovery! He is currently being housed at Sea World’s turtle rehab facility.
At this year’s Olympic and Paralympic Games, 100 percent sustainable seafood was served up to the world’s best athletes. They dined on Icelandic cod, sourced from a family-owned fishery certified by the Marine Stewardship Council.
© 2016 The Pew Charitable Trusts
Save havens for sea life
In August, President Obama expanded the existing Papahānaumokuākea Marine National Monument in the northwest Hawaiian Islands, making it the world’s largest protected area…until October when that record was broken by the establishment of Ross Sea Marine Protected Area in Antarctica. This is a particularly impressive achievement because of the international cooperation it took (24 countries and the European Union) and the productivity of these waters.
Aquarium for all
In July the Aquarium hosted its first Deaf Community Beach Walk, a follow up to the very successful Deaf Community Days we’ve started hosting at the Aquarium itself. This is just one of many examples of how the Aquarium is continuing to expand our outreach efforts to all members of our community in 2016 and beyond!
In 2016, the Aquarium had volunteers ranging from 8 to 83 years old, contributing over 85,000 hours of service as of November. It’s not an overstatement to say that there wouldn’t be a Seattle Aquarium without our amazing volunteers. Thank you!
1. You may have heard that octopuses are colorblind because they only have one kind of photoreceptor in their eyes. But did you know that recent studies may be able to explain how cephalopods could still perceive color due to the odd shape of their pupil? It’s true. Researchers at UC Berkley, Cambridge and Harvard have analyzed the shape of cephalopod pupils and the depth of the retina and modeled how the animals may be able to distinguish different wavelengths of color by controlling which wavelengths are focused on their retina at any given time. An article recently published in the Proceedings of the National Academy of Sciences may be the first part of a larger explanation for how seemingly colorblind animals can match their colors so well to the surrounding environment.
2. An octopus has a pair of organs called statocysts, sac-like structures lined with hairs, located near the brain. These are balance organs which help the octopus orient itself and maintain its position in the water. Some researchers have hypothesized that statocysts contribute to the octopus’s ability to sense vibrations, especially at lower frequencies.
3. You may know about chromatophores, cells that mechanically expand and contract, exposing different pigments to filter light. But have you heard of leucophores and iridophores? Leucophores act like diffusers to spread light to a greater area, while iridophores have ridges that structurally bend and reflect light, causing iridescent colors.
4. The common octopus, Octopus vulgaris, has been observed to untie surgical silk with its suckers.
5. Octopus muscles do not constrict. Their suction cups are capable of great suction and their muscular arms can pull with strong force, but if an octopus wrapped its arm(s) around you, you wouldn’t be in danger of suffering circulatory arrest, as you might with a boa constrictor.
6. Some octopuses can see with their skin. Opsins are light-sensitive proteins that are found in the eyes of some octopuses, as well as in their skin. Scientists from UC Santa Barbara discovered that a California two-spot octopus’ chromatophores respond to changes in light, without any light being detected by the eye. That implies that some camouflage is accomplished without being controlled by the eyes or brain.
7. While most octopuses are presumed to be loners, the Pacific striped octopus has been observed to exhibit social behavior, including living in groups. This species is also somewhat unique as one of only two octopus species that have been observed to lay more than one batch of eggs (the other is the closely related lesser Pacific striped octopus).
8. A tiny mesozoan, or parasitic worm, called Dicyemennea nouveli selectively inhabits the renal sacs of giant Pacific octopuses. The worm has no internal organs other than reproductive cells. It burrows one end into the tissue of the host’s kidney and directly absorbs dissolved nutrients. There are many other documented cases of kidney parasite species preferring specific cephalopod hosts.
The latest installment in our series of blog posts about animal families—click to read our first and second posts!
Species: Kelp greenling, painted greenling, lingcod, rock greenling
Characteristics: This family of fish is found only in the north Pacific. Interestingly, some greenlings have more than one lateral line (the sensory line down the side of a fish that detects vibrations in the water); some species have up to five! Similar to sculpins, male greenlings protect the egg masses that females lay.
Odd animal out: While most species in the hexagrammidae family are small, between seven and 20 inches, lingcod (Ophiodon elongatus) can grow to be five feet long. While that may seem large, there is an extinct species of even larger lingcod (Ophiodon ozymandias) that reached over six feet long.
Species: Pigeon guillemot, tufted puffin, common murre, Cassin’s auklet, rhinoceros auklet
Characteristics: Diving birds with short wings, short legs, and webbed feet. All 22 species live in the Northern hemisphere.
Odd animal out: Though penguins and puffins look a lot alike, penguins belong to a different family. Penguins and puffins both belong to the scientific classification Aves (birds), but penguins are in the family Spheniscidae within the order Sphenisciformes. Puffins are in the family Alcidae within the order Charadriiformes, making them more closely related to gulls and shorebirds than they are to the penguin family.
Species: Northern fur seal, California sea lion, Stellar sea lion
Characteristics: This is the family known by many different names: “sea lions,” “eared seals” (because of their external earflaps), and also “walking seals” (for their ability to rotate their hind flippers and walk, climb, and run on land).
Odd animal out: Even though fur seals have the name “seal” in their title, they are more closely related to sea lions than to “true seals” like our harbor seals, which belong to the family Phocidae (also known as “earless seals” or “crawling seals”).
In part two of our animal families holiday special, we are reminded that families—especially taxonomic families—come in all shapes and sizes. Fitting right between order and genus in zoology, the family is a special designation that ends with “–idae.” Family groups often earn nicknames like the “weasel family” for mustelidae or members of the alcidae being part of the “puffin family.” Check out these relatives and see last week’s blog post for part 1.
Species: Pacific halibut, Atlantic halibut, starry flounder, English flounder, butter sole, rock sole, C-O sole
Characteristics: This family’s name comes from the Greek roots pleura, meaning “side,” and nekton, meaning “swimmer”—these are side swimmers, or flatfish. This is actually just one of the 11 families of flatfish. Flatfish are known for having two eyes on one side of their head, and fish that belong to this family generally have both eyes on the right side of their head.
Odd animal out: Even though starry flounders belong to this right-eyed family of flatfish, individuals of this species may have both eyes on the right side of their head, or both eyes on the left side.
Species: spotted seahorse, alligator pipefish, blue striped pipefish, bay pipefish
Characteristics: This family’s name comes from the Greek roots syn, meaning “with” or “together,” and gnathos, meaning “jaw.” They all have a jaw in the shape of a tube, used for eating tiny invertebrates.
Odd animal out: The striped shrimpfish, also known as the razorfish, looks like it fits right in with this family, but it belongs to a different family (Centriscidae) within the same order (Syngnathiformes). Trumpetfish, which the Aquarium sometimes displays, are also in a separate family (Aulostomidae) within this order (Syngnathiformes).