Images 1 and 2: Living pluteus larva of the sea biscuit Clypeaster subdepressus under polarized light microscopy. Only the skeleton remains visible. Photos by Bruno C. Vellutini (Wikimedia; Flickr); cc-by-sa

Image 3: Pluteus larva via ccNeLaS

Image 4: Developing pluteus larva. Via Wikimedia. Public domain

Image 5: Sea urchin development tattoo via The Loom

Caption: “Greetings! Here’s a pic of my science tat. I studied sea urchin development for my dissertation. Upon completion 2 yrs ago, I awarded myself this tat for my academic achievement. The tat is of a sea urchin egg, 2 cell embryo, blastula, gastrula, prism stage and pluteus larval stage. Or as my friend’s say, an orange developing into an Alien face-grabber.”

Pygites brachiopods… or bizarre fossil scrotal phylogeny?

Images 1 and 2: Source. In German. 

Image 3: Source

Caption: “Pygites is unusual for a Terebratulid brachiopod. It shares many of the same features that other brachiopods in it’s order except that it has a hole in the middle of it. The hole is created as the shell grows and splits into lobes that then eventually meet back together and enclose a hollow area. This is odd behavior for a brachiopodand I’ve only seen a handful of genera that have even exaggerated lobes, such as Dicoelosia from the Haragan formation, let alone those that surround a hole. Below are three specimens from the Cretaceous (Hauterivian stage) of Spain that show you the variation in the genera.”

Image 4: ”Pygites diphyoides (d’Orbigny, 1849) from the Hauterivian (Lower Cretaceous) of Cehegin, Murcia, Spain. This terebratulid is characterized by a central perforation through its valves.” Source: Wikipedia; cc-by-sa

Image 5: Pygites diphyoides (source)

More brachiopods! The spiral lophophores are a filtering apparatus. 

Image 1: Liospiriferina rostrata (jr synonym Spiriferina rostrata) (Brachiopod). Brachiopods filtered plankton, using a specialized organ: the lophophore. It is exceptional to be able to find silicified skeleton of this organ, visible in this specimen.” via Wikipedia (image source) cc-by-sa

Image 2: Spiriferina brachiopod fossil. Science Photo Library

An example of Optical feedback

Image source:

Examples of dynamic optical feedback image on television monitor

Image source:

More information:

Volvox, a colonial green algae

From Wikipedia

“Volvox is the most developed in a series of genera that form spherical colonies.[1] Each mature Volvox colony is composed of numerous flagellate cells similar to Chlamydomonas, up to 50,000 in total,[2] and embedded in the surface of a hollow sphere or coenobium containing an extracellular matrix[2] made of a gelatinous glycoprotein.[3] The cells swim in a coordinated fashion, with distinct anterior and posterior poles. The cells have eyespots, more developed near the anterior, which enable the colony to swim towards light. The individual algae in some species are interconnected by thin strands of cytoplasm, called protoplasmates.[4] They are known to demonstrate some individuality and working for the good of their colony, acting like one multicellular organism.”

Image 1Volvox aureus, by Dennis Kunkel (2002):

Image 2: From Wikipedia, by Frank Fox (; cc-by-sa

Image 3: From Wikipedia, cc-by-sa

Image 4: Life cycle of Volvox carteri:


An electromagnetic wave bootstraps itself through the void

Image 1: Source: Wikipedia article on “Electromagnetic radiation” (image source; cc-by-sa)

Caption: “Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. This 3D diagram shows a plane linearly polarized wave propagating from left to right.”


Image 2: Source: Wikipedia article on “Electromagnetic radiation” (image source; cc-by-sa)

Caption: “This 3D diagram shows a plane linearly polarized wave propagating from left to right. Note that the electric and magnetic fields in such a wave are in-phase with each other, reaching minima and maxima together.”


Image 3: Source: Wikipedia article on “Electromagnetic radiation” (image source; cc-by-sa)

Caption: “The electromagnetic waves that compose electromagnetic radiation can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. This diagram shows a plane linearly polarized EMR wave propagating from left to right. The electric field is in a vertical plane and the magnetic field in a horizontal plane. The two types of fields in EMR waves are always in phase with each other with a fixed ratio of electric to magnetic field intensity.”

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If compression waves, like sound, need to travel through a carrier medium, then how can electromagnetic waves propagate themselves through empty space?

A photon acts a little like the Glider in Conway’s Game of Life: at each step, it creates the conditions for the next step. Now, this is just one way of viewing an electromagnetic wave, and far from complete. But it’s interesting to think about!

More quotes from Wikipedia:

“Similar to the way that a changing magnetic field generates an electric field, a changing electric field generates a magnetic field. This fact is known as Maxwell’s correction to Ampère’s law. Maxwell’s correction to Ampère’s Law bootstrap together with Faraday’s law of induction to form electromagnetic waves, such as light. Thus, a changing electric field generates a changing magnetic field, which generates a changing electric field again.”

(Source: Wikipedia article on “Magnetic field”)

“A common misconception is that the E and B fields in electromagnetic radiation are out of phase because a change in one produces the other, and this would produce a phase difference between them as sinusoidal functions (as indeed happens in electromagnetic induction, and in the near-field close to antennas). However, in the far-field EM radiation which is described by the two source-free Maxwell curl operator equations, a more correct description is that a time-change in one type of field is proportional to a space-change in the other. These derivatives require that the E and B fields in EMR are in-phase (see math section below).”

(Source: Wikipedia article on “Electromagnetic radiation”)

And it gets weirder: 

According to the special theory of relativity, the partition of the electromagnetic force into separate electric and magnetic components is not fundamental, but varies with the observational frame of reference: An electric force perceived by one observer may be perceived by another (in a different frame of reference) as a magnetic force, or a mixture of electric and magnetic forces.

Formally, special relativity combines the electric and magnetic fields into a rank-2 tensor, called the electromagnetic tensor. Changing reference frames mixes these components. This is analogous to the way that special relativity mixes space and time into spacetime, and mass, momentum and energy into four-momentum.”

(Source: Wikipedia article on “Magnetic field”)

Glider trails (Conway’s Game of Life)

Image 1: A 3D-printed version based on this thing that you can download and print! (image by Berend) 

Image 2: Source:’s_Life)

Caption: “A three-dimensional view of a glider, with previous generations visible going down the z-axis. The c/4 period is clearly visible as “stacks” of cells that remain alive for successive generations.” (cc-by-sa)

Oooooh, a Wikimedia gallery of animations from Conway’s Game of Life!

Glider (public domain). More info:’s_Life)

Gosper glider gun (cc-by-sa)