People differ on their number. For Simonides on Pentathla says they are 11, as does Aristotle in [his book] Concerning Animals,[2] but Demagoras of Samos [says] 7, and Philochorus 9.[3] Hegesander [4] tells the myth about them in his Memoirs as follows. They were the daughters of the giant Alkyoneus: Phosthonia,[5] Anthe,[6] Methone,[7] Alkippa,[8] Palene,[9] Drimo,[10] Asterie.[11] After the death of their father they threw themselves into the sea from Kanastraion, which is the peak of Pellene, but Amphitrite made them birds, and they were called Alkyones from their father. Windless days with a calm sea are called Alkyonides.
I was rummaging through Amphitrite's theoi.com page because I was searching for something that connected her to Africa (Which I did find! Specifically to the Atlas Mountains... Or perhaps Atlas himself?), and I found this absolute gem!!! Also the website I found it on is really awesome, go check it out