Two veteran illustrators take on nature study in this expanded version of Aruego’s Symbiosis: A Book of Unusual Friendships (1970), with indifferent success. Without ever actually using the term “symbiosis,” or discussing its various categories, the two present 16 cases of animal relationships. Zebras and ostriches sometimes band together to take advantage of the former’s keen hearing and the latter’s eyesight; ants will bring the caterpillar of the Large Blue Butterfly into their nest in exchange for its secretions; horse mackerels will hide within, and draw victims to, the Portuguese man-of-war’s stinging tentacles; while sooty shearwaters are “out,” reptilian tuataras will move in to clean their nests of vermin. The visuals are typically lively, all bright colors and small animal figures either smiling or grimacing toothily, but beyond endnotes supplying locales for these “weird friends,” the information is generally scanty. The fact that the caterpillar proceeds to gorge on ant larvae until driven out goes unmentioned, and does that tuatara become a permanent resident, as the narrative states, or does it depart, as the picture shows? There are no sources of further information cited for interested readers to check out, either. Rare is the child who doesn’t recognize or enjoy the art of this successful team, but these days, informational books need more than pretty pictures. (pronunciation guide) (Picture book/nonfiction. 7-9)