Possibly Shapeshifters??

I am desperately trying to find a book that meant a great deal to me when I was young, I forgot most of the details thinking I will always have the book but it got thrown away by a family member recently! I think it was called shapeshifters, was a child’s/young adults book, possibly written in the 70/80s. The front cover had a green border with foliage and possibly people on the front and/or a beach, possibly in the dark with black scales on it. It was about young adults that could shape shift. Not much to go on I know, but it would mean a lot to me if I could find it!

Could it have been a book from the animorphs series?

Is it Switchers by Kate Thompson?

Cover description made me think of Going Through the Gate by Janet Anderson. Sherwood Smith's Wren to the Rescue and other Wren books are another possibility. Long shot: Jamila Gavin's The Wormholers.