The blog of all and sundry

I just got back from a wonderful (albeit short) break to visit Australia.  Always great to see family and friends back home.

No incredibly insightful first post for the new year sadly, I’m still enjoying the lazy feeling from a relaxing (warm!) Christmas.

So instead, here are some random Wikipedia links, inspired by visits to the beaches of Coolangatta:

A siphonophora is a colony of various organisms that then appear to be a single organism.

Siphonophores are especially scientifically interesting because they are composed of medusoid and polypoid zooids that are morphologically and functionally specialized. Each zooid is an individual, but their integration with each other is so strong that the colony attains the character of one large organism. Indeed, most of the zooids are so specialized that they lack the ability to survive on their own. Siphonophorae thus exist at the boundary between colonial and complex multicellular organisms. Also, because multicellular organisms have cells which, like zooids, are specialized and interdependent, siphonophores may provide clues regarding their evolution.

(I spotted several bluebottles on Bilinga beach)

The Portuguese Man O’ War has an air bladder (known as the pneumatophore or sail) that allows it to float on the surface of the ocean. This sail is translucent and tinged blue, purple or mauve. It may be 9 to 30 centimetres long and may extend as much as 15 centimetres above the water. The Portuguese Man O’ War secretes gas into its sail that is approximately the same in composition as the atmosphere, but may build up a high concentration of carbon dioxide (up to 90%). The sail must stay wet to ensure survival and every so often the Portuguese Man O’ War may roll slightly to wet the surface of the sail. To escape a surface attack, the sail can be deflated allowing the Man O’ War to briefly submerge.

Below the main body dangle long tentacles, which occasionally reach 50 meters (165 ft) in length below the surface, although one metre (three feet) is the average. The long tentacles “fish” continuously through the water and each tentacle bears stinging venom-filled nematocysts (coiled thread-like structures) which sting and kill small sea creatures such as small fish and shrimp. Muscles in each tentacle then contract and drag prey into range of the digestive polyps, the gastrozooids, another type of polyp that surrounds and digest the food by secreting a full range of enzymes that variously break down proteins, carbohydrates and fats. Gonozooids are responsible for reproduction.

Which then led me to the fascinating article on blanket octopi:

An unusual defense mechanism in the species has evolved: blanket octopuses are immune to the poisonous Portuguese man o’ war, whose tentacles the female rips off and uses later for defensive purposes. Also, unlike many other octopuses, the blanket octopus does not use ink to intimidate potential predators, but instead unfurls a large net-like membrane which then spreads out and billows in the water like a cape. This greatly increases the octopus’s apparent size, and is what gives the animal its name.

Yikes.

A two-fer today:

Emerald Cockroach Wasp

As early as the 1940s it was reported that female wasps of this species sting a roach twice, delivering venom. A 2003 study proved using radioactive labeling that the wasp stings precisely into specific ganglia of the roach. She delivers an initial sting to a thoracic ganglion and injects venom to mildly and reversibly paralyze the front legs of the insect. This facilitates the second venomous sting at a carefully chosen spot in the roach’s head ganglia (brain), in the section that controls the escape reflex. As a result of this sting, the roach will first groom extensively, and then become sluggish and fail to show normal escape responses.

The wasp proceeds to chew off half of each of the roach’s antennae. The wasp, which is too small to carry the roach, then leads the victim to the wasp’s burrow, by pulling one of the roach’s antennae in a manner similar to a leash. Once they reach the burrow, the wasp lays a white egg, about 2 mm long, on the roach’s abdomen. It then exits and proceeds to fill in the burrow entrance with pebbles, more to keep other predators out than to keep the roach in.

With its escape reflex disabled, the stung roach will simply rest in the burrow as the wasp’s egg hatches after about three days. The hatched larva lives and feeds for 4-5 days on the roach, then chews its way into its abdomen and proceeds to live as an endoparasitoid. Over a period of eight days, the wasp larva consumes the roach’s internal organs in an order which guarantees that the roach will stay alive, at least until the larva enters the pupal stage and forms a cocoon inside the roach’s body. Eventually the fully-grown wasp emerges from the roach’s body to begin its adult life.

Learned helplessness

In part one of Seligman and Steve Maier’s experiment, three groups of dogs were placed in harnesses. Group One dogs were simply put in the harnesses for a period of time and later released. Groups Two and Three consisted of “yoked pairs.” A dog in Group 2 would be intentionally subjected to pain by being given electric shocks, which the dog could end by pressing a lever. A Group 3 dog was wired in parallel with a Group 2 dog, receiving shocks of identical intensity and duration, but his lever didn’t stop the electric shocks. To a dog in Group 3, it seemed that the shock ended at random, because it was his paired dog in Group 2 that was causing it to stop. For Group 3 dogs, the shock was apparently “inescapable.” Group 1 and Group 2 dogs quickly recovered from the experience, but Group 3 dogs learned to be helpless, and exhibited symptoms similar to chronic clinical depression.

In part two of the Seligman and Maier experiment, these three groups of dogs were tested in a shuttle-box apparatus, in which the dogs could escape electric shocks by jumping over a low partition. For the most part, the Group 3 dogs, who had previously “learned” that nothing they did had any effect on the shocks, simply lay down passively and whined. Even though they could have easily escaped the shocks, the dogs didn’t try.

This is great.

I’ve been using Amazon Turk for a variety of different projects and I love it.  It’s fantastic to actually be able to put a face to the people who do such an amazing job in contributing.

Thanks Waxy.