Everyone loves seahorses. With their trumpet-tipped snouts, gender-bending pregnant papas and tendency to dabble in monogamy, the long-necked equines of the sea have easily coiled their boxy prehensile tails around human hearts like so much sea grass.

But every family has a black sheep. Pipefish, the lesser-known, straight-bodied cousins of the common seahorse, aren’t interested in your outdated notions of monogamy. As with seahorses, pipefish males are the ones who carry eggs to term—but scientists now report that these fickle fellows can compromise their current brood of eggs if they so much as glance at a more attractive passing female.

“This is an extremely clever and insightful study… which [features] the dark side of paternal care in pipefish,” says University of Michigan biopsychologist Jacinta Beehner, who did not participate in the work. “[It] probably won’t find its way into many children’s books featuring cartoon ocean animals.”

Read the full article at Smithsonian.