Euglena sanguinea

Euglena sanguinea is a species of the genus Euglena. The red colour is due to the presence of astaxanthin and the cells can be populous enough to colour water red. The pigment is used to protect the chloroplasts from light that is too intense, but as the light levels change the cells can take on a green colour as the red pigment is moved to the centre of the cells. Euglena sanguinea is known to make the potent icthyotoxin euglenophycin. Icthyotoxin euglenophycin is a toxin that is very similar in structure to solensopsin, a alkaloid that is found in fire ant venom. This is the only known species of euglenids that is able to form toxic blooms that cause tangible losses to fish farms.