Arguments of the form “Some members of other species do X, so it is alright for humans to do so,” are pretty hopeless. Lots of creatures are just bad, if viewed in our terms. But when there are those who claim that doing X is unnatural and that it is clearly offensive to God and against the divine plan, then the news that there are a lot of animals doing X is more interesting. God clearly is more tolerant of it than those who invoke the divine will against it..
So consider the Octopoteuthis deletron, the five and a half inch little squid that lives half a mile down in the Pacific Ocean:
Over the years, scientists have added one creature after another to the list, making it clear that although nature may abhor a vacuum, it seems to be fine with just about everything else.
Male squid, for example, pay no attention to the sex of other squid. Understandably so. They live alone in the dark, males and females are hard to tell apart, and only occasionally do squids pass in the night. Far better to risk wasting a few million sperm than to miss out on a chance to reproduce.
This is only one among many sorts of same-sex sexual behavior. In some insect species, males engage in traumatic insemination, which is just what it sounds like, of other males and females alike. Among mammals, bottlenose dolphins and bonobos engage in lots of different kinds of sex. Male dolphins pursue sex with males and females equally, but the females show a preference for males. Bonobos pair off in all the combinations, often.
Laysan albatrosses form long-term female/female pair bonds, but for them the point is raising chicks, not sex. If one female can arrange a quick liaison with a male from another pair, the two females will tend the young. Noah might well have had two female albatrosses on the ark.
Not only is the squid a rather sweet looking little thing, but it also has the ability of more shallow water octopi to change its color and structure.