Placentonema gigantissima is a giant nematode that parasitizes the placenta of the sperm whale.

[2] Oral orifice oval shaped with two simple lateral lips, esophagus with two parts, one muscular and glandular.

[2] Placentonema gigantissima develops its parasitic nature by utilizing nutrients found in the endometrium of female sperm whales and forming as spiriud (small, embroyonated) eggs.

[3] It can parasitize not only the placenta, but also the uterus, reproductive tract, mammary glands, or subdermis of the sperm whale.

[5] P. gigantissima is found inside female sperm whales that inhabit lower latitudes of the southern hemisphere.