Image by Smith et al, subject to CC-BY 4.0 January 2014 Episode 8 Sign up to receive weekly alerts on new content from eLife Sign up Download Subscribe In this episode of the eLife podcast we discuss rats, ants, sharks and rays, and the pathogen that causes corn smut in maize. Lost at seaOver half of all shark and ray species are “threatened or near threatened” according to new estimates. Research Article by Dulvy et al.Insight by Bradley and Gaines. Why rats don't rat on other ratsA rat will help another rat if it is familiar with that type of rat, even if it has not met the actual rat before. Research Article by Ben-Ami Bartal et al. Complex problem solvedResearchers have worked out the structure of a protein complex that is involved in the destruction of T helper cells by HIV. Research article by Ren et al. Into the maizeThe pathogen that causes corn smut in maize employs a sophisticated strategy to increase its virulence. Research Article by Tanaka et al. Evolution at work in antsThe body shapes of queen ants and worker ants have evolved in different ways to reflect their different roles. Research Article by Keller et al.Insight by Tautz.