11 spines spiny dorsal fin seabream spines are for

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11SpinesSpiny dorsal fin (seabream) –spines are for defensePectoral finSoft fin rays of pectoral and pelvic fins (seabream)Pelvic fins
12Introduction to the ActinopterygiiActinopterygians are the largest and most successful group of fishes.With ~25,000 extant species, they make up half of all living vertebrates.First appeared in freshwater about 400 million years ago (mya), dominated 360 mya, then invaded the shallow seas and later colonized the deep sea.Mudskipper (Periophthalmus)They show a fantastic adaptive radiation into almost every conceivable aquatic niche and come in an enormous variety of sizes, shapes, colors, etc.
13Key Characteristics of Actinopterygii1. Tail is usually homocercal(symmetrical) for maximizing forward thrust. 2. Skin with mucous glands and embedded dermal (skin) scales of bony origin.3. Fins are median and paired with supporting fin rays. 4. Usually a terminal mouth with many teeth (some toothless); jaws present. 5. Gills covered by a singleoperculum(gill cover).6.Swimbladderoften present for buoyancy. 7. Most species are oviparous (i.e. produce eggs) with external fertilization.
141. Homocercal TailMulletCaudal (tail) fins are typically homocercal, or symmetrical, for forward thrust without driving the animal up or down .Diverse tail shapes depending on mode of swimming.Tuna
152. Dermal ScalesCycloid scalesCtenoid scalesScales are formed of bone from the deeper skin, or dermal layer.The trend in dermal scaleshave been to reduce weight and increase flexibility by being light and thin.Scales are absent in some to reduce drag and increase speed.AnnulusExposed partFocusCirculiFocusCteniiAnnuli
162. Dermal Scales (ctd.)Actinopterygian scales are overlapping and partially embedded in the skin.The lateral line systemsenses vibrations close to the fish and has modified scales.Lateral lineCtenoid scales of a black seabreamBlack seabream (Acanthopagrus schlegelii)
3. Segmented Fin RaysThe thin, segmented fin rays(lepidotrichia) of actinopterygians are flexible and delicately articulated with the skeleton, thus allows for greater maneuvrability.Segmented fin rays of caudal finWaspfish juvenileCowfish Lionfish (venomous spines)
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