Degrades chitin, chitotriose and chitobiose. May participate in the defense against nematodes and other pathogens (By similarity). Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide (1->4)-beta-linkages in chitin and chitodextrins. Monomer. A small proportion is lysosomal. Highly expressed in tongue, stomach, kidney, brain, skin, testis, and bone marrow. Low level of expression was found in lung, heart, spleen, small intestine, and liver. Not detectable in pancreas, salivary gland, large intestine, uterus, or peripheral blood mononuclear cells (PBMC). Belongs to the glycosyl hydrolase 18 family. Chitinase class II subfamily.