Category Archives: Marine

Sharks in the Hudson

Smooth Dogfish Shark, photo credit Patrick Kerwin at New York Times City Room blog

It always amazes me how animals and plants will reclaim habitat if it becomes even slightly more habitable from a prior polluted state. Yesterday I was walking along Battery City Park when I saw a two foot shark on the walkway. A couple had stopped ahead of us and I believe convinced the man who had caught it to throw the shark back into the murky waters. Before it was thrown back–to hopefully live out the rest of its days enjoying mollusk and crustacean meals–its eyes glinted green, huge in relation to its body.

It is listed as “Near Threatened” by the IUCN (Florida Museum of Natural History), so hopefully the Hudson continues to become a hospitable home to the dogfish shark and other marine creatures.

These random encounters are always a great reminder of the diversity that exists all around us, if we just pay attention. What surprising animal diversity has caught you unawares lately?

More Reading:

NY Sharks & Whales

Smooth Dogfish Shark

Review of War of the Whales by Joshua Horwitz

War of the Whales

War of the Whales

(Check out that link, if only to hear the echoing sonar)

I’ve been on a bit of a book kick lately and still have a pile waiting for me. I definitely recommend this one on whales, the Navy, and the legal system all the way up to the Supreme Court. Although, if your views run anything akin to mine, you will need to find a sturdy wall to bang your head against at multiple points.

Meticulously researched for 6 years, this book weaves together complex and competing national security, environmental, and legal concepts. It illuminates impacts of human activity that are not often considered. Human activity has permeated everywhere. Even the deep ocean is haunted by our sounds.

Exhibit One: “Of the 200 [marine mammals in 1999] that stranded alive [on U.S. shorelines], some were euthanized on the beach by Fisheries officials. Most of the others soon died of exposure to the elements, or suffocated when their bodies collapsed under their own weight, or drowned when the high tide washed over their blowholes. Only five marine mammals that stranded alive that year were actually rescued from the beach and returned to the ocean.” (pg. 70).

Exhibit Two: “The Marine Mammal Protection Act had been on the books for almost 20 years, but the Navy had never applied for a permit–as the law mandated–for any experiment or exercise that might ‘injure or harass’ any marine mammals.” (pg. 162) Essentially, underwater sonar activities went unregulated until the mass stranding in 2000 set activists in motion.

Exhibit Three:  “[A key lawyer] Reynolds wondered if saving the whales was simply a grandiose fantasy. Having barely escaped commercial whaling, were the survivors doomed to be overrun by the ceaseless naval arms race after more and more powerful acoustic weapons? Would judges and politicians continue to defer to admirals in their ‘balance of hardships’ calculations, until there were no more whales left to save?” (pg. 344-345)

Resources:

American Cetacean Society

Cuvier’s Beaked Whales

Washington Post Book Review

Review of Octopus! The most mysterious creature in the sea (by Katherine Harmon Courage)

“Head-turning intelligence is turning out to be far less rare in the animal world than we once presumed (which makes us the dummies for assuming we were the only ones with any wherewithal at all.” (Courage, 119)

I recently read Octopus! by Katherine Harmon Courage. Already one of my favorite animals for their intelligence and camouflage abilities, I loved delving into the lives of these cephalopods. I could have done without the chapters on eating octopus, as they are off my list of edibles due to their intelligence and charisma, but with over 250,000 tons caught annually, I understand why she included information about the importance of the octopus catch and octopus cuisine. (Especially as we exhaust fisheries and begin eating our way down the marine food web, with species depleted quickly in many regions.)

But the book really gets going after that portion. I could nerd out about all of the octopus facts, and the remarkable diversity of octopuses (e.g., blanket octopuses, venomous blue-ringed octopuses, or the Giant Pacific Octopus) but I want to provide a brief overview of their camouflage tricks and encourage you to read the book.

Octopuses are considered to be the smartest invertebrate. Oddly enough for solitary animals, they learn well through observation, while also engaging in complex behaviors that were not taught (like tool use). They are able to change color, texture, and reflectivity in well under a second to blend in with their background. How do they change so fast? According to Courage, “Teams of researchers and millions of dollars have not yet been able to fully understand or even begin to replicate it” (83). We don’t know how they deal with all of the environmental stimuli, as light scatters everywhere underwater and the ocean bottom is a festival of textures and colors. To hide in plain sight, they use chromatophores to change color, iridophores to change reflectivity and hue, leucophores to adjust white coloring, and muscles to create texture. It’s still not clear how they ‘know’ what to shift to. Scientists think that they may be processing the input locally and instantly, without involving their central nervous system. Not bad for a creature that Aristotle deemed stupid.

http://katherinecourage.com/book/

More Resources:

Octopus Adorabilis

Octopus Movement

Octopus

Ten Curious Facts

An ode to an octopus

Mimicry delight

Turning in fright

A splash of ink

Makes you think


Why can’t I obscure

And slink into nooks

Hidden and demure


And outwait the danger

Without looking stranger

Than the ocean floor

Just another background, nothing more


The whole thing is worth watching, but after minute 4:15 is absolutely stunning.

Other Resources:

http://ocean.si.edu/ocean-news/how-octopuses-and-squids-change-color

http://animals.howstuffworks.com/marine-life/octopus-camouflage.htm

Happy Exploring!