Australia’s Giant Cuttlefish in Trouble as Weak Spawning Season Continues

Australian giant cuttlefish may be in trouble, as evidenced by low summer spawning numbers (flickr| richard ling)

This summer, numbers are way down.

Australia’s ABC Radio recently interviewed a local commercial fisherman who reported that he has only seen four this year—rather than the usual “hundreds of thousands.” Other news outlets have been picking it up too.

Researchers say the low numbers are cause for concern, and they don’t yet know what’s causing the trend (though “BHP Billiton’s proposed desalination plant” nearby probably won’t help. It would reportedly pour “huge quantities of hypersaline wastewater” into Spencer Gulf and make the area unpalatable for a variety of species). A new study finds that the cuttlefish breeding colony had decreased by 78% in the past decade, and last year marked a record low.

Plan to Exonerate Hawaiian Monk Seals Relies on Reality-TV-style Cameras

Hawaiian Monk Seal photo by: U. S. Fish and WIldlife Service

The image rehabilitation plan comes as local fishermen ramp up  claims that the seals have been depleting area fish stocks. Recent cases of people pestering—and in some cases killing—the seals have come partly as a reaction to these rumors, and spurred scientists to “glue submersible cameras onto the seals’ backs, using the footage to prove to fishermen the animals are not harming their way of life.”

You can find out more about habitat threats to monk seals or read Les Welsh’s blog post from April about people intentionally killing the seals in the waters around Kaua’i (and how you can help).

Video: Blue Shark Chomps Giant Squid

Giant squid are mysterious, awesome and locked in an eternal arms race with sperm whales. Live sightings are so rare that even footage of a recently dead Architeuthis is a pretty big deal. Recently, Australian angler and journalist Al McGlashan came across a largely-intact carcass whose bright red coloration indicated it had died recently. While he filmed, a blue shark tore into the squid, thus launching  the best cephalopod viral phenomenon of 2012 (so far…I eagerly await your videos of octopuses singing ‘Call Me, Maybe’). Take a look at Field & Stream’s exclusive full-length video and photos right this second.

Click here to view the embedded video.

Canadian Lobster is Blue, Yet in Decent Spirits

Canadian lobster boat captain Bobby Stoddard caught a lobster in early May that resembled a giant Avatar cat person. That’s the way we say ‘it was blue’ in America now.

Blue lobsters do occur, but they’re uncommon. According to The University of Maine’s Lobster Institute, “only an estimated one in two million lobsters is blue” (which makes them rare, but not quite as rare as live, naturally red or yellow lobsters, which are estimated at one in ten million and one in 30 million, respectively). Blue lobsters come about due to “a genetic defect that causes the lobster to produce an excessive amount of a particular protein.”

You can learn more about invertebrates in our Wildlife Library.

Manta Ray Ultrasound Sheds Light on Liquid Oxygen Intake

A study recently published in Biology Letters is the first to show how manta ray embryos get oxygen, based on video from an ultrasound performed on a pregnant ray in 2008.

Though manta rays, like many other cartilaginous fish, give birth to live young, they lack an oxygen-giving umbilical cord or placenta. According to researchers, “the baby ray was raising and lowering its jaw, pumping uterine fluid in through its mouth and spiracle.” The continuous regulated flow of the fluid over the ray’s gills allowed the embryo to extract oxygen (the baby was “a healthy female, 2 meters from wingtip to wingtip and weighing 50 kilograms” at birth). According to Taketeru Tomita, a fish biologist at Hokkaido University Museum, this is the first time that scientists have observed fetal viviparious vertebrates pumping liquid to extract oxygen.

Great Whites Summering in Cape Cod

Researchers tag a shark near Chatham, MA, in 2009. Tagged great whites recently returned to Cape Cod to feed on seals. (flickr | Massachusetts Energy and Environmental Affairs)

Researchers say the sharks were drawn to the area by “a growing seal population on Monomoy Island,” redoubt of migrating birds and other non-humans for hundreds of years. They haven’t come close enough to tourist beaches to warrant any official warning, though mayhem will presumably occur if the star-crossed Brody family gets too close.

For more on ocean creatures, see Kevin Coyle’s post from last year about animals’ various methods of swimming or my post about the Top 5 Real Sea Serpents (including the giant squid). You can also check out an article about sperm whales and the threat posed to them after the oil spill in the Gulf  of Mexico.

If you’ve seen a story that you think should be covered in the next Ocean Wildlife Roundup, please let me know in the comments below, email me at greenbergm@nwf.org, or tell me on Twitter @MaxTGreenberg.

Giant squid eyes are huge, farsighted, and well-adapted to detecting predators (flickr | Jonathan Lampron)

Now, though, we know a little more.

According to a study published in Current Biology, the giant squid (and ‘colossal squid‘)’s huge eyes—which, aside from being the largest eyes of any known animal, are proportionally larger than those of other squid—have evolved for a special purpose:

…such giant eyes are unlikely to evolve for detecting mates or prey at long distance but are instead uniquely suited for detecting very large predators, such as sperm whales. [...] we predict that, below 600 m depth, (the eye) would allow detection of sperm whales at distances exceeding 120 m [...] we hypothesize that a well-prepared and powerful evasive response to hunting sperm whales may have driven the evolution of huge dimensions in both eyes and bodies of giant and colossal squid.

Lead author Dan-Eric Nilsson, a marine vision expert at the University of Lund in Sweden, and his team determined that giant squid are lousy at seeing things up close—they’re farsighted—and good at seeing big things off in the distance. This offers a unique and much-needed advantage when your primary day-to-day threat to life and limb (and limb, and limb, and limb…ha!) is a 60-ton predator with nature’s most powerful sonar system.

Duke Today:

But the boost in being able to sense contrast, which large eyes provide, is critical for detecting the low light differences of large, distant objects, the most important one being the bioluminescence stimulated by large animals such as approaching sperm whales, [report contributor and Duke biologist Sonke Johnsen] said.

Giant squid washed ashore in Norway, 1954 (flickr | NTNU-Vitenskapsmuseet)

The team realized that sperm whales dive and swim continuously while emitting sonar to ping the squid. The cephalopods are deaf to the sonar, but the whale’s wake triggers small organisms like plankton to produce light. Based on the design of the squid’s eye, the animal could see this light, though contrast is low, over “freakishly long distances,” about 120 meters — the length of an American football field, Johnsen said.

We all know that Duke basketball is evil and lame, but Duke biology is evidently quite useful.

The giant squid’s massive eyes are (presumably) the latest stage in an epic arms race against sperm whales—a specific, complex adaptation that justifies their tremendous metabolic expenditure. The big eyes allow squid to spot sperm whales by their glowing wake from about 390 feet away, through murky expanses of deep ocean water, and escape—despite the predator’s sonar and speed.

For more on ocean creatures, see Kevin Coyle’s post from last year about animals’ various methods of swimming or my post about the Top 5 Real Sea Serpents (including the giant squid). You can also check out an article about sperm whales and the threat posed to them after the oil spill in the Gulf of Mexico.