Geneticists often refer to the “genome” of a species, the DNA sequences that specify the development and physiology of an animal. In reality though, the genome is only a set of instructions for creating that individual, it is the RNAs and proteins within each cell that carry out the DNA’s … Read more about Warm Hearts for White Sharks
A Slap Upside the Head
Thresher sharks are among the most impressive of elasmobranchs, their scythe-like tails nearly equaling their bodies in length. Many hypotheses have been proposed for the function of these elongated tails. Do they aid in swimming? Attract potential mates? Serve as a warning … Read more about A Slap Upside the Head
Sharks and Birds: Showing Off For the Ladies
Satellite tagging allows both terrestrial and marine animals to be followed remotely over long periods of time. While financial and technological drawbacks to this methodology exist, satellite tags are effectively used to track many different species. For marine animals, among the most … Read more about Sharks and Birds: Showing Off For the Ladies
Future Predators Avoid Becoming Prey
Electroreception is the ability of certain marine vertebrates to detect minute electrical charges transmitted through the water. The shark electroreceptor system is composed of sensory organs called ampullae of Lorenzini, that lie within small pores across the head of the shark. All … Read more about Future Predators Avoid Becoming Prey
Report from Oslob
It’s been a while since I wrote on this blog, mostly because I’ve spent the last year on sabbatical visiting whale shark aggregations around the world – Djibouti, Philippines, Mexico.... It’s a rough job but someone has to do it! Seeing so many whale shark aggregations in a short time really lets … Read more about Report from Oslob
Do Sharks See Color?
Elasmobranchs have highly developed sensory systems that help them find food - a sense of smell that can detect prey at long distances, and the ability to read the minute electrical fields emitted by fish. But what about their vision? Do sharks see in color? Two recent studies use … Read more about Do Sharks See Color?
Shark Strandings Investigated
Sharks strand, or beach themselves, with some frequency in certain coastal areas. This phenomenon is seen in other marine creatures as well, and is particularly common in dolphins and small whales. It’s a frustrating occurrence, as the cause for strandings is rarely known, and most … Read more about Shark Strandings Investigated
A Nose By Any Other Name
While we’re on the subject of noses, let’s talk about sawfish. Sawfish are elasmobranchs, the group of animals that includes sharks, rays and skates. While sawfishes appear “shark-like”, with their elongated bodies and tall dorsal fins, they are actually a type of ray. Sawfish are … Read more about A Nose By Any Other Name
Building a Shark Nose
Vertebrates smell using their olfactory system, a complex organ composed of tissues in both the nose and the brain. In mammals where the sense of smell has been well studied, the front line of the olfactory system is a tissue called the olfactory epithelium, the layer of cells lining the … Read more about Building a Shark Nose
The Far-Reaching Hand of Anthropogenic Change
More shark history this post. Not fossilized extinct sharks this time, but the use of historical records to trace the extinction - more correctly extirpation, more on that later - of a shark population in recent history. The Saint Peter and Saint Paul Archipelago is often called Saint Paul’s … Read more about The Far-Reaching Hand of Anthropogenic Change
400 Million Years and Counting
There’s an often-reported statistic that sharks have remained unchanged for 400 million years. What does this really mean? Our familiar sharks weren’t around 400 million years ago, and what do we really know about the extinct shark species that have existed between then and now? Fischer … Read more about 400 Million Years and Counting
Sharks in Decline
We all know sharks are in trouble. We talk about the dramatic declines in shark populations, a result of high catch rates for shark fin, and as bycatch in fisheries targeted at other species. But what is the data these statements are based on? How are such declines … Read more about Sharks in Decline