Staff at 74 universities walked out on Thursday on the first of 14 days of unprecedented industrial action over a long-running dispute over pay, pensions and working conditions.
UCU general secretary Jo Grady said the support sent a "clear message to universities" that the should be working together to "work things out. We have been clear that we are always ready to seriously discuss all the issues at the heart of the disputes," she said.
A Universities and Colleges Employers' Association spokesman commented that universities were "deeply disappointed" that the strikes were going ahead.
The disputes are believed to centre on changes to the universities' pension scheme, the Universities Superannuation Scheme (USS), that the UCU report mean members will pay more for their pension but will ultimately lose tens of thousands of pounds in retirement.
Staff are also angry at universities' failure to make significant improvements on pay, equality, casualisation and workloads.
The strikes will largely take place between this Thursday and Friday, Monday and Wednesday next week as well as on March 2, 5, 9 and 13. It is the second wave of strikes in the disputes after UCU members took part in eight days of action before Christmas.