What is this book about?
This book is about chondrichthyan fishes (chondros + ichthys, literally
“cartilaginous fishes”), a term that includes the subgroups of elasmobranchs
(sharks, skates, and rays) and holocephalans (chimaeras), and is organized
around common and not-so-common questions about these spectacular
animals.
As a shorthand device and to avoid continually saying “sharks, skates,
rays, and chimaeras,” we refer to the overall group of chondrichthyans as
“sharklike fishes,” at least where all subgroups share a trait. Where dif-
ferences occur or unique traits deserve mention, we are more specific. To
avoid confusion, we use the technical term “selachians” (or “true sharks”)
when we mean sharks in the sense that most people think of them (the
torpedo-shaped predators with prominent fins and big teeth that appear on
the Discovery Channel). The term “batoids” refers to the more flattened
skates, rays, and sawfishes (think of bat rays if that helps), and “chimaeras”
is the general term for the strange-looking holocephalans. Also, ichthyolo-
gists (fish researchers) have agreed that common names of species are capi-
talized, so we talk about “Whale Sharks” and “White Sharks,” but we don’t
capitalize “reef sharks” and “dogfish sharks” because those names refer to
groups, not just one species.
The questions posed in this book often seem simple and elementary
(for example, “Do sharks have to keep swimming to breathe?”). The an-
swers, however, are often anything but simple because of the diversity and
complexity of body types, species, ecology, anatomy, behavior, and physiol-
ogy and the special solutions that sharks (and skates and rays and chimae-Chapter 1
Introducing
Sharks, Skates, Rays,
and Chimaeras