Dolphins – at Play?

Thunder & Lightning for an Early Morning Trip

We were with the same group (about 15-20 dolphins) for the entire trip. While most of the group chose not to interact with the swimmers, a few individuals came closer and seemed interested. One juvenile male had a plastic bag draped over his pectoral fin on our second entry. He passed it gracefully to his flukes and dorsal fin and dropped it in front of a swimmer. We saw him on two more entries before he left the bag with us … we did not leave it for him to play with more.

One other dolphin that we saw near to the end of our trip was an adult … I'm not yet sure of it's gender because I have not yet reviewed the video. But it was holding half the body or a rather large fish. I doubt it was eating the fish, but the dolphin treated the fish as a sort of trophy … several other individuals were following it as they sped past us underwater.

Dolphins, like other animals, will play with objects, like the bag or fish described above, or they will play with one another. It is sometimes hard to distinquish between play and fighting behaviors, especially in older individuals. Let me expand a bit …

Play vs. Aggressive Behavior – Play often is characterized by mock fighting behaviors that are modified with subtle cues (postures or approach angles) reminding peers that the intent of ongoing activities is not truly aggressive. Play occurs in young animals during the formation of long-term social attachments (e.g., friendships), and while young learn the meaning and proper use of the signals in their social structure. The same actions characterizing aggressive behavior in adults could have an entirely different meaning when used by a juvenile – the context is modified. It is highly possible that behaviors (e.g., jaw claps, hits) are not specific to particular expressions of aggression, unless modified by or coupled with a specific posture or approach.
A good example of play versus aggression is the 'S'-posture reported for many cetaceans (see photo). This posture has the head 'up', anterior ventral surface (i.e., chest) 'down', peduncle 'up', and flukes 'down'. I observed this posture from old and young spotted and bottlenose dolphins alike during play and aggressive contexts. During play, juveniles gave a modified 'S' with oblique angles of approach and much rubbing contact. During aggression, the posturing dolphin, usually a male, performed the 'S' maneuver toward conspecifics accompanied by direct approaches, a bubble cloud, jaw clap, and often hits.