Fish refers to one or more individuals of the same species; fishes refers to more than one species.

Transcription

1 Fish refers to one or more individuals of the same species; fishes refers to more than one species.

2 a. A fish is as an aquatic vertebrate with gills, fins, and usually a skin covered with scales. a. It is estimated that there are more than 28,000 living species of fish; this is more than all other species of vertebrates combined. Fish dominate the world s seas, lakes, and streams.

3 d. Many animals that are called fish, really are not. Some animals that are NOT fish include: i. Jellyfish, cuttlefish, starfish, crayfish, and shellfish.

4 e. Likewise, many animals that are fish, do not have the word fish in their name. Some animals that ARE fish include: i. Seahorses, eels, sharks, rays, and skates.

5 a. Fish were the first vertebrates; their fossils date back to the Cambrian Period, about 550 million years ago. b. Unlike today's fish, the earliest fish had no scales, paired fins, or jawbone. a. These early fish and a few of today s jawless fish belong to the Superclass Agnatha- meaning no jaw. According to the fossil record, these jawless fishes lived relatively unchanged over the following 100 million years. Ostracoderm

6 c. About 450 million years ago, in the Silurian Period, fish appeared that had a jawbone and paired fins. Known as the gnathostomata (jawed vertebrates), they were large predators and the ancestors of all future vertebrates.

7 i. Jaws are thought to have evolved from the first pair of gill arches (the skeletal elements that support the pharynx). ii. Jaws allowed fish to seize and manipulate their prey. i. Paired fins increased fishes stability and maneuverability in the water.

8 d. The Devonian Period (about 360 to 400 million years ago) is nicknamed the Age of Fishes, because of the abundance and diversity of fishes that appeared during this period. i. All four living classes of fish and the three subclasses of Osteichthyes were established by the mid-devonian. ii. However, many species of fish that lived during the Devonian are now extinct, such as a well-known group of fish known as Placoderms (armored fish). 1. Dinichthys herzeri is an extinct, giant, marine arthrodire placoderm from the Late Devonian of Ohio and Tennessee.

9 a. Body shape- Fish are streamlined which allows them to move rapidly in water. b. Coloration- Most species of fishes are countershaded in which the dorsal (top) surface is darker than the ventral (underneath) surface.

10 membranous, wing-like or paddle-like organs attached to any of various parts of the body of fish and some other aquatic animals; used for propulsion, steering, or balancing. Which fins are considered paired fins? Pelvic fins Pectoral fins

11 d. Buoyancy- Bony fish can store gases (in their swim bladder) and cartilaginous fish store lipids (in their liver) to help aid in buoyancy to maintain their vertical position in the water. e. Circulation- Fish have a twochambered heart and singleloop blood circulation. f. Efficient respiration- Fish have internal gills for gas exchange. Gills fan out in water and have a lot of surface area.

12 g. Homeostasis- Fish maintain concentrations of salt and water that differ from their surroundings. i. Marine bony fishes are hypoosmotic regulators. 1. The tissues of marine fish are less salty than the surrounding water, so water continually leaves the body of a marine fish through its skin and gills. To keep from becoming dehydrated, a marine fish drinks large amounts of water and produces a small amount of concentrated urine. In addition, its gills are adapted to secrete salt.

13 ii. Freshwater fish are hyperosmotic regulators. 1. The tissues of a freshwater fish are saltier than its surrounding environment, so water is continually entering the body of a freshwater fish through its skin and gills. To overcome this, freshwater fish do not drink water, and they produce large amounts of dilute urine.

14 i. Sight- fish eyes are similar to the eyes of land vertebrates. 1.Most fish do not have eyelids, however many sharks do. ii.sound- Fish have internal ears from which they receive vibrations from water through their body. iii.smell and Taste- They have the ability to detect chemicals in the environment, called chemoreception. Fish have nostrils (nares) and taste buds. Taste buds may be found in their mouth or on lips, fins, skin, and barbels (whiskerlike organs).

15 1.Lateral Line System- Fish have a system of canals in their skin that allow them to sense vibrations in the water. The lateral line system is composed of neuromasts (receptor organs highly sensitive to vibration and water currents).

16 2. Ampullae of Lorenzini- These organs are located in a cartilaginous fish 's head and can detect the bioelectric fields generated by and surrounding living animals (muscles).

17 i. Temperature control- Fish are poikilothermic ectotherms. i. Poikilotherms are animals whose body temperature adjusts depending on the environment. ii.ectotherms are animals that primarily gains heat through the environment.

18 Fish belong to: Kingdom Animalia Phylum Chordata Subphylum Vertebrata

19 i. Osteichthyes Bony fish (account for about 96% of all fish species) ii.chondrichthyes Cartilaginous fish sharks and their relatives iii.myxini hagfish iv.cephalaspidomorphi lampreys

20 a. Living jawless fish include approximately 108 species divided between two classes. b. Members of both groups lack jaws, internal ossification, scales, and paired fins. c. Both groups share pore-like gill openings and an eel-like body form.

21 Class Myxini includes 70 species of hagfish i. Hagfish are marine, bottom-dwellers scavengers or predators that feed on dead or dying fish. ii.despite being blind, hagfishes are quickly attracted to dead and dying fish by their keen senses of smell and touch. iii.a hagfish enters a dead or dying animal through an orifice (body opening) or by digging into the body; it then rips and eats pieces using two toothed, keratinized plates on its tongue that fold together in a pincher-like action.

22 iv. One of the most well-known and gross features of a hagfish is their ability to produce enormous quantities of slime. When roughly handled, hagfish excrete a milky fluid from special glands positioned along its body. When the fluid comes in contact with seawater it forms slime so slippery that the animal is almost impossible to grasp. Videos: One, Two, Three

23 Class Petromyzontida includes 38 species of lampreys i. Lampreys can be marine or freshwater, and free-living or parasitic. ii.parasitic lampreys attach themselves to their host with a disc-shaped mouth and feed on the blood and body fluids of other fish. Like leeches, lampreys inject an anticoagulant into the wound to promote blood flow.

24 i. All lampreys ascend freshwater streams to breed. Marine forms are anadromous, meaning that they leave the sea where they spend their adult lives to swim up streams to spawn. 1. Using their oral discs to lift stones and pebbles and vigorous body vibrations to sweep away light debris, they form an oval depression in which to nest. 2. At spawning, with the female attached to a rock to maintain her position over the nest, the male attaches to the dorsal side of her head. As eggs are shed into the nest, they are fertilized by the male. The sticky eggs adhere to pebbles in the nest and quickly become covered with sand. 3. Eggs hatch in about 2 weeks, releasing small larvae that look nothing like their parents. The larvae live as filter (suspension) feeders while growing slowly for 3 to 7 or more years, and then rapidly metamorphose into adults.

25 4. Parasitic freshwater adults live 1 to 2 years before spawning and then die; anadromous forms live 2 to 3 years. 5. Nonparasitic lampreys do not feed after emerging as adults and their digestive tract degenerates to a nonfunctional strand of tissue. Within a few months they spawn and die. Various Lamprey Mouths: Various Lamprey Species: Video

26 Video Sea Lamprey, Petromyzon marinus Invasion of the Great Lakes by the sea lamprey, Petromyzon marinus, has devastated fisheries. No lampreys were present in the Great Lakes west of Niagara Falls until the Welland Ship Canal was deepened between 1913 and 1918, allowing lampreys to bypass the Falls. Moving first through Lake Erie to Lakes Huron, Michigan, and Superior, sea lampreys, accompanied by overfishing, caused a total collapse of a multimilliondollar lake trout fishery in the early 1950s.

27 a. Class Chondrichthyes includes sharks, rays, skates, and chimeras. i. Almost all chondrichthyans are marine; only 28 species live primarily in freshwater.

28 b. Have skeletons made of cartilage (a flexible, lightweight material made of cells surrounded by tough protein fibers). i. Although calcification may be extensive in their skeletons, bone is entirely absent throughout the class. Cartilage Skeleton Bone c. Have skin covered with small tooth-like spines called placoid scales.

29 i. Cartilaginous Fish use internal fertilization. 1.Males have modified pelvic fins called claspers, used in copulation to transfer sperm to female. Male Female

30 ii. All chondrichthyans have internal fertilization, but maternal support of embryos is highly variable. i. Some sharks and all skates lay large, yolky eggs immediately after fertilization; these species are termed oviparous. Some deposit their eggs in a horny capsule called a mermaid s purse (figure A). Embryos are nourished from the yolk for a long period (6 months-2 years) before hatching as miniature replicas of adults. Mermaid's purses from a clearnose skate (Raja eglanteria) on top and a chain dogfish (Scyliorhinus retifer) on bottom

31 2. Many sharks are ovoviviparous species which retain developing young in the uterus while they are nourished by contents of their yolk sac until born. 3. Still other species have true viviparous reproduction in which the embryos receive nourishment from the maternal bloodstream through a placenta, or from uterine milk, secretions produced by the mother. 4. Some sharks, including sand tigers, exhibit a gruesome type of reproduction in which embryos receive additional nutrition by eating eggs and siblings. Modes of Reproduction: Viviparous- Born alive from their mother Ovoviviparous- Develop from an egg inside of their mother and then born Oviparous- The mother will lay an egg and the pup is born from that Bonnethead shark and litter Offspring are called pups and receive no parental care after the eggs are laid or young are born. Newborn Lemon shark giving birth shark pup

32 i. Fusiform body shape- like a torpedo, shark bodies are designed to reduce water resistance. ii. Sharks possess a heterocercal caudal fin, in which the dorsal portion is usually larger than the ventral portion to provide forward thrust and some upward lift as it sweeps back and forth. iii.sharks have a hard time breathing and maintaining buoyancy when they stop swimming. i. A shark s caudal fin and stiff pectoral fins generate lift as the fish swims.

33 2. Sharks also store large amounts of lipids in the large lobes of their liver. Lipids are less dense than water and will help aid in their buoyancy.

34 iv. Sharks have a rectal gland to help remove excess sodium and chloride ions from the body. They also convert ammonia to urea in their bodies and store large amounts of urea to help balance their inner solute concentration with the solute concentration in their saltwater surroundings.

35 Sharks are well equipped for their predatory life. 1.Many teeth- Predator sharks have 6-20 rows of teeth. When a front row tooth wears down or breaks, the back replacement teeth shift forward. This ensures sharks always have sharp teeth. a.one shark may use more than 20,000 teeth during its lifetime. 2.Sharks may initially detect prey from a kilometer or more away large olfactory organs (capable of detecting chemicals as low as 1 part per 10 billion) and the lateral-line system.

36 3. At closer range a shark switches to vision as the primary method of tracking prey. a. Contrary to popular belief, most sharks have excellent vision, even in dimly lit waters. 4. During the final stage of attack, sharks are guided to their prey by the bioelectric fields that surround all animals. a. The ampullae of Lorenzini are electroreceptors located primarily on a shark s head. b. Sharks may also use electroreception to find prey buried in the sand.

37 5. Although most sharks are by nature timid and cautious, some of them are dangerous to humans. a. Over 375 shark species have been identified, but only about a dozen are considered particularly dangerous. Three species are responsible for most human attacks: great white sharks (Carcharodon carcharias), tiger sharks (Galeocerdo cuvier), and bull sharks (Carcharhinus leucas). b. More shark casualties have been reported from tropical and temperate waters near Australia than from any other. c. Shark attacks are usually accidental and rarely end in fatalities.

38 d. Worldwide there are about shark attacks annually resulting in about 5-15 deaths. e. The International Shark Attack File (ISAF) is the longest running database on shark attacks and is the only globally-comprehensive, scientific shark attack database in the world.

39 vi. Not all sharks are predators- some of the largest sharks (whale shark and basking shark) are filter feeders and use gill rakers to filter the water for microorganisms.

40 1. The smallest shark is the Dwarf Lantern Shark which is only about 8 inches long. 2. The largest shark is whale shark (Rhincodon typus), which can grow to 60 feet long. 3. The shortfin mako (Isurus oxyrinchus) is the fastest shark swimming at speeds of up to 20 miles an hour. 4. The Spiny Dogfish Shark can live more than 100 years. This is exceptional when you consider the average life span of most species is 20 years. 5. Between 20 and 100 million sharks die each year due to fishing activity. 6. Sharks are known as eating machines but because they are ectothermic, some sharks eat only about 2 percent of their body weight each day. That's a bit less than humans typically eat. ^ Dwarf Lantern Shark ^ Shortfin Mako ^ Spiny Dogfish Shark

41 i. Rays and skates are cartilaginous fish with flattened bodies and flexible wing-like pectoral fins and often long tails. ii. Ray vs. Skate 1. The major difference between rays and skates is in their reproductive strategies. Rays are live bearing (viviparous) while skates are egg laying (oviparous), releasing their eggs in hard rectangular cases sometimes called "mermaid s purses". 2. Skates typically have a prominent dorsal fin while the dorsal fin is absent or greatly reduced in rays.

42 3. Rays have diamond or disk-shaped bodies; skates have triangular-shaped bodies. 4. Skates have small teeth while rays have plate-like teeth adapted for crushing prey. 5. Rays are generally much larger than skates.

43 i. Primarily bottom dwellers feeding on mollusks and crustaceans. ii.while lying on the bottom of the ocean, skates and rays draw water into their gills through spiracles (two large openings on top of their head, behind the eyes). Gill openings are on the underside of the head, but the large spiracles are on top. Respiratory water enters through these spiracles to prevent clogging the gills, because the mouth is often buried in sand.

44 Pacific electric ray (Torpedo californica) is one of 14 described species of electric rays. a. The electric rays are named for their ability to generate and discharge a strong electric current to stun prey and for defense from potential predators. The kidney-shaped electric organs are visible through the skin on the dorsal surface of these animals. b. Divers are warned to avoid contact with the ray, as the shock of 45 volts or more is powerful enough to knock down an adult human.

45 Manta Ray (Manta birostris) 1.The manta ray (Manta birostris) is the largest ray reaching up to 9 meters in width. This ray feeds on plankton and small fish and are completely harmless to humans. Video: One, Two, Three

46 Atlantic Stingray (Dasyatis sabina) is one of 200 described species of stingrays. a.stingrays come in two different general types i. Benthic or bottom-dwelling ii.pelagic or swimming (also known as nekton) b.benthic rays, such as the Atlantic stingray, are often found buried in the sand. c.stingrays have venomous spines along or near the base of the tail. The muscular whip-like tail can be lashed about quickly in defense.

47 a. Occasionally beach-goers will accidentally step on stingrays that are partially buried in the sand near the beach resulting in a painful, serious wound in the foot. Although the spines are dosed with venom, wounds are not normally lethal. However, it is still important to get medical attention as soon as possible to avoid any potential infection. b. Humans should do the "stingray shuffle" when walking along sandy bottoms close to the beach. This gives any stingrays in the vicinity enough warning that they are able to swim away.

48 i. Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, ratfish, spookfish, or rabbitfishes. ii. A chimaera has a big head with large eyes and a snout in front of its eyes, which is shaped somewhat like a duck's bill. iii.many species have a sharp, poisonous spine in front of the first dorsal fin on the top of their body. The chemicals released by the spine seem to be only mildly poisonous to humans but can inflict a painful wound. iv.over 31 species of chimaeras exist, and most live in deep water on the continental slopes. Some chimaeras, including the elephant fish (Callorhinchus capensis), occur on the continental shelves and may range close inshore, but none are found in fresh water. v. All lay eggs in distinctive spindle-shaped, finned egg-cases.

49 G. Class Osteichthyes includes more than 28,000 species of Bony Fish a. Have skeletons made of bone and cartilage. i. This type of skeleton is very strong and provides a strong site for which muscles can attach and pull. b. Fish secrete a layer of mucus that covers its entire body. i. The antiseptic mucus layer helps protect a fish from infection, bacteria, fungus, and disease.

50 c. Many species of bony fishes have a gas-filled bladder called a swim bladder. i. The swim bladder originally developed in fish as an organ of respiration, as evidenced by the "lung" of the lungfishes. ii.in modern bony fish, the swim bladder helps the fish control floatation and buoyancy.

51 1. Without a swim bladder, bony fish sink because their tissues are more dense than water. 2. To achieve neutral buoyancy, they displace additional water by a volume of gas in a swim bladder, thus adjusting their total density to match that of the surrounding water. This adjustment allows fish with a swim bladder to remain suspended indefinitely at any depth with no muscular effort. 3. Early bony fishes had to gulp air to fill their swim bladder; modern bony fishes fill and deflate their swim bladder by secreting and absorbing their own gases into and out of their blood.

52 d. Most bony fishes have an operculum composed of bony plates attached to muscles that covers the gills on each side of the head. i. Movements of the operculum allow the fish to pump water over the gills and allowing it to breathe. ii.this enables them to pump water without having to swim, unlike sharks. This enables it to conserve energy.

53 a. Bony fishes show great variety in body shape. i. A laterally compressed (flattened, side-to-side) body shape is common in bony fishes that live in dense cover or within coral reefs. ii. A depressed (flattened, topto-bottom) body shape is common in bottom-dwelling fishes. iii.an elongated shape like that of an eel. iv.others look even more unique, for example seahorses and seadragons.

54 f. Most fish have a homocercal tail, where the fin appears superficially symmetric. This can be expressed in a variety of shapes.

55 g. Most species of bony fishes are covered with and protected by a layer of light, thin, flexible scales. i. They overlap from head to tail, an arrangement that helps reduce drag as a fish swims.

56 ii. There are three different kinds of bony fish scales: 1.Cycloid a.cycloid scales are circular and smooth. 2.Ctenoid a.ctenoid scales have a characteristic toothed edge. 3.Ganoid a.ganoid scales are diamond-shaped, shiny, and hard.

57 iii. Most bony fishes have cycloid or ctenoid scales. 1. As a fish grows, cycloid and ctenoid scales add concentric layers. 2. Growth is temperature dependent. Consequently, fish living in temperate regions grow rapidly in summer when temperatures are high and food is abundant but nearly stop growing in winter. Annual rings in the scales reflect this seasonal growth, a distinctive record to determine a fish s age. Count the rings to determine the fish s age:

58 3. Some bony fishes may have scales only on portions of their body, and some species have no scales (such as most eels and catfishes). i. Most fish are dioecious, with external fertilization and external development of their eggs and embryos (oviparity). ii.eggs and sperm are released from fish through an opening behind the anus. i. Some aquarium fish are an exception. Ovoviviparous guppies and mollies bear their young alive after development in the ovarian cavity of the mother.

59 iii. Mortality is very high among the eggs and young fish so to compensate and ensure that at least a few survive fish will lay a very large number of eggs. iv. Spawning is the egg laying behavior of fish and varies widely with bony fish. 1. Some build nests from plants, sticks, or shells. 2. Some carry the eggs in their mouths. 3. Some come together in great schools and release vast numbers of gametes into the water to drift with currents. 4. Some guard their eggs; some do not. 5. Some migrate. a. Catadromous fish spend most of their lives in freshwater but migrate to the sea to spawn, such as freshwater eels. b. Anadromous fish spend their adult lives at sea but return to freshwater to spawn, such as salmon.

60 Bony fish may be divided into two smaller classes: i. Lobe-Finned Fish- Class Sarcopterygii i. Named after their fins, each fin consists of a long, fleshy muscular lobe that is supported by a central core of bones; the b ones form joints with one another; Muscles within the lobe move the fins.

61 2. Represented today by Lungfishes and Coelacanth 3. Terrestrial vertebrates (early amphibians) arose from one lineage within this group. Coelacanth Queensland lungfish, Neoceratodus forsteri

62 1.Named after their fins, each fin is supported by long, segmented, bony elements called rays that support and stiffen each fin; There are no muscles within the fins; muscles within the body move the fins. 2.A huge and diverse modern assemblage containing nearly all familiar freshwater and marine fish.

63 Lionfish, Pterois volitans Lionfish are an invasive species threatening Florida's saltwater fish, wildlife and habitat. Native to the reefs and rocky crevices of the Indo-Pacific, these fish have now found their way to warm ocean habitats worldwide. Florida pet owners are blamed for their release into unfamiliar waters. Believe it or not, DNA evidence traces all lionfish in the Atlantic back to only six to eight female lionfish.

64 i. The venomous, fast reproducing fish are aggressive eaters and will consume anything and everything, gorging so much they are actually getting liver disease. With no known predators -- except human beings -- they can wipe out 90% of a reef. ii. They produce 30,000 to 40,000 eggs every few days and are sexually mature by 1 year old. Today, you can find them throughout the Amazon, Bahamas, Caribbean and in the waters along North Carolina. "The lionfish invasion is probably the worst environmental disaster the Atlantic will ever face," said Graham Maddocks, president and founder of Ocean Support Foundation

65 c. The needle-like dorsal fin spines of this species deliver a venomous sting that can last for days and cause extreme pain, sweating, respiratory distress, and even paralysis. i. The venom of the lionfish is purely defensive. It relies on camouflage and lightning-fast reflexes to capture fish and shrimp prey. Video One, Two

66 Videos: One, Two, Three The largest bony fish is thought to be the ocean sunfish (Mola mola) which can grow to lengths of up to 11 feet and weights of over 5,000 pounds. Mola mola larva Produces more eggs than any other vertebrate on earth. One modest-sized female can have 300 million eggs inside her!

67 The smallest bony fish is thought to be the dwarf pygmy goby (Pandaka pygmaea) which grows to a whopping length of just about one-third of an inch. The Dwarf Pygmy Goby is an endangered fish primarily found in the Philippines. These fish are native to freshwater environments, but have also been forced into marine habitats because of industrialization and pollution. Since the Malabon River does not place high priority on protecting these tiny fish and the waters in the neighboring areas are all heavily polluted, the species is actually considered extinct in the Philippines.

68 Sailfish are the fastest fish in the world and can keep pace with the Cheetahs on land that can run as fast as 70 mph. Sailfish can grow to 3 meters in length and 200 lbs. Video

69 Mekong giant catfish Giant Barb Arapaima European catfish