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).
People often spend time with family during the holidays, so we thought we would take a look at some animal families—as in the scientific classification, not in the generational way like the sea otter family at the Seattle Aquarium. (Did you know that we have three generations of sea otters? Grandmother Lootas, daughter Aniak and granddaughter Sekiu. Learn more about them here!)
Similar to our biological or adopted families, there are attributes that these animals share with their families. And there’s often a black sheep or two.
Species: Northern sea otter, North American river otter, American mink
Characteristics: Long-bodied, short-legged carnivores
Odd animal out: The sea otter is unique in this family for being the largest member and the only marine species. It also lacks the anal scent glands that are typical of this family. Skunks, which are famous for their scent glands, actually belong to a separate family (Mephitidae).
Species: Black-bellied plover, killdeer
Characteristics: Small to medium-sized shorebirds with large, round heads, large eyes, and short bills. Instead of hunting by probing and feeling with their bills, like most shorebirds, this family hunts by sight.
Odd animal out: The killdeer is a shorebird that you don’t always find by the shore! They are often spotted on lawns, golf courses, driveways and parking lots.
Species: Clown anemonefish, false clown anemonefish, blue green chromis, blackfin chromis, Hawaiian sergeant major, black spot sergeant major, Pacific gregory
Characteristics: Mostly marine, mostly tropical, territorial fish with bodies that are often compressed laterally (from side to side).
This Thanksgiving, all of us at the Seattle Aquarium are thankful for:
You! Since 1977, the Seattle Aquarium has been dedicated to serving Seattle and the Puget Sound area in working to fulfill our mission of Inspiring Conservation of Our Marine Environment. The Aquarium welcomes over 800,000 visitors each year, local residents and tourists alike, to explore our exhibits, many of which focus on the ecosystems of Puget Sound and Washington’s coastal waters.
Our members and donors, who provide critical support for our education and conservation programming, including providing marine science education for over 40,000 local schoolchildren each year; performing research on local species like the sea star; and training volunteer beach naturalists who teach visitors to Puget Sound shorelines how to enjoy the fragile nearshore habitat without hurting the animals that call it home.
Our incredible volunteers. In 2015, 1,335 volunteers donated 100,032 hours of service to the Seattle Aquarium, representing a donated value of over $2.3 million!
New climate change legislature. This year, the Paris Agreement was formally ratified, galvanizing the climate action that will help restore the health of Earth’s one ocean.
Our staff, who have put in countless hours rehabilitating and caring for a variety of critters. From Rialto the sea otter pup to Tucker the olive ridley sea turtle, we’ve loved nursing animals back to health—and sharing highlights with you along the way.