The Southern Calamary Squid (Sepioteuthis australis) can be seen both day and night at a number of sites in Sydney. They often travel in numbers but once they are large enough they tend to travel alone. When they feel threatened they can quickly launch at your face and release their ink - so be prepared for that as it is not a nice experience! I like taking photos of these guys and I think they find the process of photography exciting too as they often pose for the shot.
