Sloths’ mysterious teeth decoded

Like most mammals, we humans have a variety of tooth types for different purposes: incisors, for gripping, canines for ripping and tearing, and molars (also pre-molars) for grinding and chewing. But one group, known as the Xenarthra (a particularly excellent name meaning “strange joints”), have very simple dentition, with similar, unrooted teeth which lack enamel and…

Cartilage and encroaching bone in the developing mouse skeleton

This shot of the dorsal neck of a developing mouse embryo visually shows the process of skeletal growth found in all bony vertebrates. The widespread blue stain (Alcian blue) reveals the extensive cartilaginous blueprint for the growing skeleton, which extends by the division of chondrocytes (cartilage-producing cells) guided by signalling molecules across the embryo. The…

Gene expression patterns in developing Drosophila flies

In this image we see 16 Drosophila melanogaster fly embryos, photographed during their development under a confocal microscope. Fluorescent markers for different proteins have been injected into the embryo, so researchers can see exactly where they are expressed (produced). The labelled proteins here are involved in organising the embryo into different parts as it develops, so we can…

Juvenile file clam, Lima

Bivalves are molluscs with two shells, such as oysters, mussels and clams. As adults, these are all sessile, unable to move far from their anchor point on rocks and other surfaces. But movement is necessary to avoid overcrowding and food shortages – these animals have mobile larval and juvenile stages which are pelagic (move through the water…

Developing lobster egg

Developing lobster egg, with eye and legs visible at the bottom left and right, respectively. Image courtesy of Tora Bardal and the Nikon Small World competition.