Ozopore the Sclerosomatidae secrete short-chain acyclic ketones and alcohols, and the Phalangiidae, naphthoquinones. In millipedes, ozopores are repeated serially on body segments, and usually situated laterally. Exceptions are members of the order Glomerida, which have ozopores located dorsally. Some members of the order Julida have especially prominent ozadenes. Ozopore An ozopore is the opening of a defensive gland present in some arthropods, notably in millipedes of the order Polydesmida and in harvestmen, the eight-legged arachnids also known as "daddy long-legs". The glands themselves are known as ozadenes, also called "scent glands", "repugnatorial glands", "odoriferous glands" or "stink glands" by various authors.
Opabinia family tree is that modern tardigrades may be "Opabinia"s closest living evolutionary relatives. Although Zhang and Briggs (2007) disagreed with Budd's diagnosis that "Opabinia"s "triangles" were legs, the resemblance they saw between "Opabinia"s lobe+gill arrangement and arthropods' biramous limbs led them to conclude that "Opabinia" was very closely related to arthropods. In fact they presented a family tree very similar to Budd's except that theirs did not mention tardigrades. "Opabinia" made it clear how little was known about soft-bodied animals, which do not usually leave fossils. When Whittington described it in the mid-1970s, there was already a vigorous debate about