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The fish on the cover of Identity and Data Security for Web Development is a long-tail seamoth (Pegasus volitans) also known as the batfish, sea dragon, or dragonfish. They are covered with bony plates arranged in concentric rings and their pectoral fins are large and winglike. Seamoths live in shallow coastal waters with beds of seagrass or seaweed and sandy or silty bottoms.

Most seamoths measure 5 inches (13 cm) but the long-tail seamoth measures 7 inches (18 cm). Despite their name, the large fin muscles of a seamoth are not strong enough for flapping flight. The fins are most useful to change a predator’s view, quickly expanding to add width and depth to a seemingly nondescript fish. The mouth is situated on the underside of a long snout, which indicates seamoths are bottom feeders; feasting on minuscule animals that live among the grains of sand. They are poor swimmers and do not travel far, yet are widely dispersed across oceans because their larvae are carried thousands of miles by ocean currents as part of the plankton. The seamoths have dispersed themselves throughout the coastal waters of the southern Pacific and Indian Oceans all the way to South Africa. They cannot survive the cold barrier in the sea off the Cape of Good Hope, so they have yet to reach the Atlantic Ocean.

Many of the animals on O’Reilly covers are endangered; all of them are important to the world. To learn more about how you can help, go to animals.oreilly.com.

The cover image is from Wood’s Natural History. The cover fonts are URW Typewriter and Guardian Sans. The text font is Adobe Minion Pro; the heading font is Adobe Myriad Condensed; and the code font is Dalton Maag’s Ubuntu Mono.