Jawless fishes belong to the superclass Agnatha in the phylum Chordata, subphylum Vertebrata. Vertebrates comprise all species of animals within the subphylum Vertebrata (chordates with backbones). Each of these terms describes a valid taxon, phylum, subphylum or family. The Asterozoa are a subphylum in the phylum Echinodermata. Krill belong to the large arthropod subphylum, the Crustacea. The Pezizales are an order of the subphylum Pezizomycotina within the phylum Ascomycota. Horseshoe crabs resemble crustaceans but belong to a separate subphylum of the arthropods, Chelicerata. Vertebrates (Latin for "joints of the spine") are a subphylum of chordates. Balanus is a genus of barnacles in the family Balanidae of the subphylum Crustacea. A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata. The subphylum Medusozoa includes all cnidarians with a medusa stage in their life cycle. For this reason, the vertebrate subphylum is sometimes referred to as "Craniata" when discussing morphology. It belongs to the Western Saharan subphylum of Nilo-Saharan. They live in a symbiotic relationship with a fungus belonging to the subphylum Basidiomycota. Mucoromycotina is a subphylum of uncertain placement in Fungi.