Brown recluse spider cephalothorax (Loxosceles reclusa). Characteristic features are the six eyes arranged in three pairs at the front of the head and the fiddle-shaped marking on the back. The brown recluse spider is often called the "violin" spider or "fiddleback" spider. The bite of this spider is nasty and results in open, ulcerating sores. Left untreated, such bites often become infected and significant tissue necrosis can occur.
Convict cichlid skin (Cichlasoma nigrofasciatum). The convict cichlid, Cichlasoma nigrofasciatum (formerly known as Archocentrus nigrofasciatum), is a laterally compressed cichlid with an oval body shape. The body color is white to very light gray with eight or nine transverse black bars. It is an aggressive fish despite its size. Fish skin like many other vertebrates (amphibians, reptiles, birds, mammals) consists of two principal layers - superficial epidermis and deeper dermis. The epidermis consists of two or more layers. The deepest is a series of closely packed, discrete cells called the germinal layer, or stratum germinativum. The outer epidermal cells are formed from the germinal layer. Body fish slimes are produced by epidermal cells and their degradation. Epidermal cells can have highly convoluted surfaces that retain slime that has a primary function of protection from pathogens and parasites.
Kidney glomerulus (podocytes and capillaries of the renal corpuscle). The glomerulus consists of a tightly coiled network of capillaries surrounded by podocytes. There about 1 million glomeruli in each kidney. Podocytes have narrow cell extensions (processes) that in turn give rise to secondary extensions called pedicels. The podocytes completely surround the capillary system. As blood passes through each glomerulus, water and metabolic wastes are filtered through capillary walls by the surrounding podocytes. About 100 litres of blood are filtered every hour. The water and waste pass into the lumen of the Bowman's capsule. From the capsule the water and waste draiins into the surrounding tubules where reabsorption occurs.
Immature bobtail squid (Euprymna scolopes). A symbiotic relationship exists between a luminescent bacterium and the squid. The bacteria in ocean environments causes the squid to produce a mucus substance that is secreted below the light organ on the squid. Cilia are used to draw more bacteria into this mucus matrix. The bacteria migrate into the light organ and colonize an area within it. They provide a light source for the squid to make it blend in with the ocean floor at night. Thus predators have a hard time seeing the squid.