To understand a particular Bible verse one must see it in context with other verses, and to take it literally and not allegorize it: (if something is allegorized it can then mean whatever you want it to mean.) This is a case in point:-
Rev 8:8-11 KJV And the second angel sounded, and as it were a great mountain burning with fire was cast into the sea: and the third part of the sea became blood; (v.9) And the third part of the creatures which were in the sea, and had life, died; and the third part of the ships were destroyed. (v.10) And the third angel sounded, and there fell a great star from heaven, burning as it were a lamp, and it fell upon the third part of the rivers, and upon the fountains of waters; (v.11) And the name of the star is called Wormwood: and the third part of the waters became wormwood; and many men died of the waters, because they were made bitter.
Don Koenig in his commentary on the Book of revelation says:-
8 And the second angel sounded, and as it were a great mountain burning with fire was cast into the sea: and the third part of the sea became blood;
9 And the third part of the creatures which were in the sea, and had life, died; and the third part of the ships were destroyed.
After the second angel sounds, a very large segment of this comet crashes into the sea. A third of the sea becomes as blood due to the red dust from the explosion of the metallic body. All life in the sea over this portion of the earth will die and all ships on it will be destroyed. This could mean a third of one sea but I think it actually means one third of all the ocean surface on earth since the next judgment is on one third of the land surface on the earth.
The Sirens.
They aren't. Mermaids are the product of sightings of ordinary sea creatures and the overactive imaginations of sailors.
No. Sirens are mythological creatures that lure sailors to their doom by their voices, they had no use for 'plunder'.
In Greek mythology, sirens were creatures that lured sailors to their doom with their enchanting voices, causing ships to crash on the rocks. The sailors who heard the sirens' song were unable to resist its allure and would steer their ships towards the dangerous rocks, leading to shipwrecks and death.
The sirens were monsters that led sailors to a drowning death by singing so sweetly that sailors jumped off their boats to meet them.
Yes, the giant squid was long believed to be a sailors' legend, but it is a real animal.
If you are asking 'what enticed sailors to their doom' then that would be the sirens or syrens (based on the origin) if you are asking 'how did they entice sailors to their doom' then that would be their voices. The Sirens (syrens) are vulture-like creatures (although some origins depict them as mermaid type creatures) with hypnotising voices, the voices allow the hearer to glimpse what they want most. When the hearer heads towards the 'dream world' the crash into the jagged rocks and die, the sirens then feast on them.
The collective noun for 'sailors' is a crew of sailors, whether there are two sailors or hundreds of sailors.
crew
sailors'
Crew
A crew of sailors.