Here are photos of invertebrates found in the field. Strange arthropods like whip scorpions and sun spiders especially fascinate me. If some of these critters grew to dog size we'd all be lunch. Fortunately, however, terrestrial arthropod body size is limited because the weight of their exoskeletons increases proportionally with their body surface area. If they grew too big, they wouldn't be able to carry their skeletons. Lobsters and king crabs get away with their large sizes because bouyancy helps support their weight.