Lab Quiz 4: Guide to McKee Key

• Adipose Eyelid; A fatty transparent tissue covering the eye in some fishes
• Adipose Fin: A fleshy, fin-like, rayless structure situated on the dorsal ridge between the dorsal and tail fins, which in some species is fused to the tail and separated from it only by a slight notch

  
• Anal fin: The vertical fin on the lower/ventral side of fishes just anterior to the tail and behind the anus

  
• Anterior: referring to the forn portion of the body, fins, or other body part, often used with other directional terms
• Anterior nasal flap: A flap that partially divides the nostrils into 2 openings (1 for incurrent and 1 for excurrent)

  
• Appressed: Pressed close together against something
• Axil: The armpit/backside of the pectoral fin
• Axillary (accessory) scale: A modified, usually elongated scale attached to the upper or anterior base of the pectoral/pelvic fins in certain herring-like fishes
• Bilobed: Bearing 2 lobes/divided into 2 lobes
• Brachyodont: Teeth with relatively short crowns not extending far beyond the gum line
• Branchial filter plate: A spongy modified gill structure orientated in horizontal plates and found in devil rays & whale sharks; used for filtering plankton
• Branchiostegal membrane: A membrane/membranes situated on the ventral edges of the gill covers and containing the elongated branchiostegal rays
• Cephalic: referring to the head region
• Cirri / Cirrus: A small fleshy appendage(s)
• Confluent: Merging together to form a single mass; a fin type around some eels
• Concave: Arched inward; a concave fin is one in which the central soft rays/spines are shorter than the anterior and posterior soft rays/spines, thereby causing an inward distal edge to the fin
• Convex: Arched or rounded outward; a convex fin is one in which the central soft rays/spines are longer than the anterior & posterior soft rays of spines, thereby causing an outwardly curved distal edge to the fin
• Crescentic: Lunate or arched, as in the shape of the moon during its first/last cycle
• Crossband: Referring to a marking on the pectoral fin that extends obliquely to vertically across the fin rays
• Crumenal Organ: A gizzard-like organ found behind the 4th fill arch in Argentine fishes, gill rakers extend into the pouch-like organ and interdigitate to grind ingested food
• Ctenii: tiny prickles/minute spines, rough to the touch
• Cusp: Any of the projection either pointed/rounded on the surface of a tooth
• Decurved: Curved downward/bent
• Dental Plate: Modified tooth-like structure
• Diastema: Gap between 2 teeth
• Diel: A cyclic occurance over a 24 hour preiod
• Disc: referring to a rounded body shape of rays or batfishes: also referring to the modified pelvic fins of clingfish and gobies; also referring to the modified dorsal fin of remoras
• Distal: Located away from a point of origin or near the posterior edge
• Dorsal fins: The fins of the midline of the back; usually 2, a spiny-rayed dorsal followed by a soft rayed dorsal which may or may not be connected
• Emarginate: Having a notched/slightly concave margin; refers to shape of caudal fin
• Entire: Having a smooth edge and without serrations
• Esca: A fleshy bulb-like structure located at the distal end of the angling apparatus (illicium) characteristic of goosefishes, batfishes, and frogfishes
• Exserted: Extending beyond the margin of the membrane
• Falcate: Curved like a sickle; a fin is falcate when it is deeply concave, having the middle rays much shorter than the anterior and posterior rays
• Finlet: Separated parts of divided dorsal and anal fins
• Frenum: A connecting membrane restricting the movement of a body part or organ as seen in some fishes between the upper jaw and snout
• Genital papilla: A small blunt, fleshy, projection behind the anal opening present in gobies
• Gonopodium: Male copulatory organ found in livebearers
• Grammistin toxin: toxin present in the mucus of Soapfish that is toxic to other fish and dissuades predators
• Groove: A depression channel or shallow indentation, may be short or long