Aquarium creatures

 Feather stars (aka crinoids)

Underside of a starfish

(More below the fold)

Nyctosaurs

An illustration by paleo-artist Mark Witton, showing some very odd pterosaurs: 

 

Found via this old post on Tetrapod Zoology, from which I also learned that baby pterosaurs are called "flaplings."

A sample from the abyss

All the tiny creatures in this image came from a sample of ocean-floor sediment.

Image from Deep Sea News.

Characodictyon

This is an electron microscope image of a tiny fossil from the Precambrian era, the shell of a microbe (somewhat resembling modern radiolaria). It may be the oldest example of armor on a living creature. 

Image from Live Science. 

Holiday lights

Collection of seahorses

Seahorses are displayed at an endangered species exhibition at London Zoo. ( Dan Kitwood/Getty Images)

From Boston.com's 50 best photos from the natural world. 

Micro-plants

Illustrations of algae, plants, seaweed, and fungi from Common Objects of the Microscope, by John George Wood, 1900:

Creatures of Europa

Diagram of hypothetical life-forms on Jupiter's moon Europa, from an old issue of New Scientist.

Europa's icy shell may also contain large embedded "lakes" which, like the ice fissures, might provide an abode for life.

Predators of the Cambrian

A cool CGI reconstruction of Cambrian-era creatures found fossilized at the Burgess Shale:

The two large swimming predators are Hurdia and its cousin Anomalocaris-- the latter of which had very sharp eyes:

The fossils represent compound eyes -- the multi-faceted variety seen in arthropods such as flies, crabs and kin -- and are amongst the largest to have ever existed, with each eye up to 3 cm in length and containing over 16,000 lenses.
The number of lenses and other aspects of their optical design suggest that Anomalocaris would have seen its world with exceptional clarity whilst hunting in well-lit waters. Only a few arthropods, such as modern predatory dragonflies, have similar resolution.
The existence of highly sophisticated, visual hunters within Cambrian communities would have accelerated the predator-prey 'arms race' that began during this important phase in early animal evolution over half a billion years ago

Diatom mandala

This beautiful design fits on a microscope slide, and the jewel-like objects that compose it are the shells of tiny marine microbes.

Image from Klaus Kemp's diatom art site. Diatom arrangements like these, along with similar arrangements of butterfly scales, were popular in the Victorian era.

Frosty leaves

Vowels and vestigial air sacs

Over millions of years, changes to our vocal organs have allowed us to produce a rich mix of sounds. One such change was the loss of the air sac - a balloon-like organ that helps primates to produce booming noises.

All primates have an air sac except humans, in whom it has shrunk to a vestigial organ. ...

To find out how this changed the sounds produced, Bart de Boer of the University of Amsterdam in the Netherlands created artificial vocal tracts from shaped plastic tubes. Air forced down them produced different vowel sounds, and half of the models had an extra chamber to mimic an air sac.

De Boer played the sounds to 22 people and asked them to identify the vowel. If they got it right, they were asked to try again, only this time noise was added to make it harder to identify the sound. If they got it wrong, noise was reduced.

He found that those listening to tubes without air sacs could tolerate much more noise before the vowels became unintelligible.

The air sacs acted like bass drums, resonating at low frequencies, and causing vowel sounds to merge...

Observations of soldiers from the first world war corroborate de Boer's findings. Poison gas enlarged the vestigial air sacs of some soldiers, who are said to have had speech problems that made them hard to comprehend.

From New Scientist.

Fairy wasp

[above] The fairy wasp, Megaphragma mymaripenne... pictured next to a Paramecium and an amoeba at the same scale.
...
As they get smaller, insects can do away with many of their organs. The feather-winged beetles – twice as big as the fairy wasps, but still impressively tiny – have drastically reduced the size of their genitals, guts and breathing tubes. They have totally lost their hearts: at their size, diffusion is enough to carry liquids around their body without the need for a pump. Their wings, like those of thrips and fairy wasps, are little more than wispy strands, rather than the flat oars of most other insects. That’s all they need to paddle through thick air currents.

From Not Exactly Rocket Science.

Periphylla

 The helmet jelly Periphylla. 

Image © 2011 Deep Sea Conservation Coalition

Raven deixis

Ravens are amazingly smart birds, possessing reasoning abilities previously thought to be uniquely human. Now, they have been observed performing a very human-like form of nonverbal communication:

From early childhood on, children frequently use distinct gestures to draw the attention of adults to external objects. So-called deictic gestures such as "pointing" ("look here") and "holding up of objects" ("take this") are used by children for the first time at the age of nine to twelve months, before they produce their first spoken words. Scientists believe that such gestures are based on relatively complex intelligence abilities and represent the starting point for the use of symbols and therefore also human language. Deictic gestures are thus milestones in the development of human speech.
Surprisingly, observations of comparable gestures in our closest living relatives, the great apes, are relatively rare. Chimpanzees (Pan troglodytes) in the Kibale National Park in Uganda, for example, use so-called directed scratches, to indicate distinct spots on their bodies to be groomed. Deictic gestures thus represent an extremely rare form of communication evolutionarily and have been suggested as confined to primates only.

 Full story at Science Daily.