A herd, an aggregation or in some cases an Army.
herd
Murder
Good question no manatees do not have to be in a group but most manatees are.
There are 1000 manatees
Manatees eat only sea grass, which is why they are called seacows.
Manatees often swim alone, but it is not uncommon for them to form groups, especially when seeking areas of warm water. Groups of manatees are called aggregations or herds.
You are most likely right. If you want, why don't you edit that for them?
West Indian manatees!
calf
Manitie
calf. The calf is also for cow. Remember manatees are also called sea cows so mabye there's where they got the name
Manatee Fat
They get killed for their flesh for oil lamps. Manatees also get killed by the carelessness of humans speeding on their motor boats and accidentally hitting the manatees! Also, there is a disease called the Red Disease and that kills many manatees also!
Manatees are consumers.