There is no individual relay. Then it would not be a relay. You are probably thinking of an individual medley.
In all swimming events there are four swimmers in a relay
There is no such thing as 4x400 medley relay swimming event.
A starting block
There are 8 relay teams per a heat. There are 4 people in each relay.
swimming competition is when people swim in a contest like event, where they swim against the other members of other swim teams and they do different events and one is called a relay and the score the relay to see who wins.
swimming polo relay medley 25m/100m/200m/250m/500m/900m
anywhere form 6-8
butterfly, backstroke, breastroke, freestyle, IM, medley relay, freestyle relay
The cannon relay is the last race in a gala. The fastest boy and girl in each year group come together as one swimming team and race the other teams.