The Calling of Saint Peter and Saint Andrew
Church of Sant'Apollinare Nuovo, Ravenna
In Matthew 4:18-20 and Mark 1:16-18 Jesus sees Simon and Andrew casting their nets into the sea. He invites them to come with him and be "fishers of men." Andrew is not mentioned in Luke's somewhat different account of the call (5:1-11). In John's gospel (1:35-42) he is one of two disciples of John the Baptist who decide to follow Jesus. Andrew then recruits his brother Simon, whom Jesus renames "Cephas, which is interpreted Peter."
In the boat Simon and what must be Andrew cast the net into a sea teeming with fishes. Simon has the same gray hair and short, square beard that he wears elsewhere in these mosaics. At the oars, Andrew has wild hair, as is common in early portraits of him and seen again in the scenes of the loaves-and-fishes miracle and the Garden of Gethsemane. He wears a simple gray tunic; Simon's is white and striped, like the togas on the apostles in the other panels. Jesus invites the two with a blessing gesture, his fingers in the "Old Believer" configuration.
The man on the far right dressed as an apostle probably does not represent anyone in particular. If he is anyone, he could be the evangelist telling the story, the unnamed second disciple in John, or even Andrew referring his brother to Jesus (in which case the other man in the boat would simply be a fellow fisherman, lacking the striped white tunic because he is not being called to discipleship).
This image in full resolution
See also a view of the entire left wall with commentary on the iconography of Jesus and the apostles in these mosaics.
More of St. Peter
More of St. Andrew
More of the Public Life of Jesus
Photographed at the church by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.