Saturnyn The Saturnyns , or Saturnynians , were an aquatic species from the planet Saturnyne . The females of the species were also known as Sisters of the Water . Biology . The Saturnyns had human , fish and crustacean traits . They had a humanoid upper body , a fishlike head with sharp teeth and a lobster - like lower body . Though they could survive on land , they needed a lot of water , which they could drain from other creatures . They also had a strong sensitivity to ultraviolet light and were incinerated by large amounts . The children may be connected to their mother as Rosanna Calvierri indicated that when she died , her race would end . Indeed , the Doctor no longer seemed to consider the 10 , 000 Saturnyn in Venice ' s waterways a threat anymore and they stopped making any sort of noticeable movement or noise right after Rosanna was consumed . ( TV : " The Vampires of Venice " ) Technology . On Earth , the Saturnyns used a variation of perception filter technology to disguise themselves . Though it gave them the appearance of human s , it accidentally gave them vampire - like qualities . Since the technology couldn ' t hide reflections and the human brain couldn ' t process the two conflicting pieces of information , they had no reflections in mirror s . Their fangs would also be seen when they fed , due to the human subconscious perceiving danger and attempting to alert the conscious mind . The Saturnyns were capable of gradually converting humans into Saturnyns by draining them of their blood and replacing it with Saturnyn blood . They could also control the weather , causing storms and earthquake s . ( TV : " The Vampires of Venice " ) History . During the Time Lord s war with the Great Vampire s , the Saturnyns were caught in the crossfire , and the whole species were turned into vampires . ( PROSE : " The Multi - Faceted War " ) Some time in the species ' history their home - world was besieged by the cracks in the universe , ranging from small cracks to cracks that consumed the planet ' s sky . At first the cracks appeared to pose no danger and the aliens were able to observe other worlds through some and " silence " and the " end of all things " through others . Finally , the true nature of the cracks became apparent and Saturnyne was lost . Deciding to take their chances with the cracks that showed other worlds , the Saturnyns fled to worlds with oceans like their own planet . One group made it to Venice in 1580 , led by a female known as Rosanna Calvierri , along with her children . Only the male children survived , though there were ten thousand of them . To rectify this problem and save their species , Rosanna lied about an outbreak of the plague , quarantining the city . She took in young girls under the pretence of providing them an education . Once amongst them , Rosanna and her son would drain them of blood and replace it with Saturnyn blood , converting them into Saturnyns . Rosanna also intended to create a tidal wave that would sink the city of Venice , providing them a habitat to live in . When they took in Isabella , they attracted the attention of the Eleventh Doctor , Amy Pond , Rory Williams , and Isabella ' s father , Guido . They investigated the school , enrolling Amy to get in . Though she opened the trap - door to let the others in , she was captured . With Isabella ' s help , they escaped , though Isabella was dragged back and later killed for treason . Rosanna sent the converted girls and her son Francesco to stop them while starting the process to sink Venice . The females were all killed when Guido blew up the house when they attacked , while Francesco was killed when Amy directed sunlight on him . The Doctor disabled the device . With her plans thwarted and her species doomed , Rosanna killed herself by jumping into the water with her perception filter on . Her children , not knowing who she was , devoured her . Rosanna ' s last words indicated that her children would then die as she asked if the Doctor could deal with another dead race on his conscience . ( TV : " The Vampires of Venice " ) Other references . The Doctor considered his encounter with the Saturnyns particularly memorable . He mentioned them while describing Rory and Amy ' s time in the TARDIS . ( TV : " A Good Man Goes to War " ) He also mentioned them again later . ( TV : " Let ' s Kill Hitler " ) Amy Pond also made several references to the Saturnyns . ( PROSE : " The Glamour Chase " , COMIC : " Attack of the 50ft Rory " ) Rory also made references to the Saturnyns . ( PROSE : " Paradox Lost " )