The Animal Allies series (4 titles) highlights examples of symbiosis within the animal kingdom. While most of the series deals with mutualism, this title examines commensalism, a relationship in which one animal benefits but the other isn’t harmed. Here the arctic fox’s strategy of following polar bears to share in their kills is revealed. The text is written in a narrative style that will draw in readers, and it smoothly incorporates general facts about polar bears and arctic foxes, such as physical descriptions, position on the food chain, diet, and hunting abilities. The final chapter touches on challenges related to climate change. Large photos appear on every page, and “Did You Know?” fact boxes are scattered throughout. The book concludes with additional polar bear and arctic fox facts and stats.

The animal pairs in this series work together to hunt and capture prey. After an opening chapter describing their teamwork in action, the individual creatures are introduced, with commonalities and differences noted. This leads into the process of their combined hunting efforts. Readers learn how complementary qualities, like the grouper’s speed and the moray’s eel’s ability to squeeze into tight spaces increase chances of success. The authors note that not all symbiotic relationships work the same, with clear focus on the practicality of cooperation in terms of survival. Photographs are useful, if not especially dynamic. Many focus on just one animal, though several show the two species teaming up, either during or after the hunt. Useful captions are attached to some, but not all photos. Closing pages note the threats facing both animals. VERDICT Well-executed introduction to animal symbiosis.