By: Daymis Rosa & Maria Escobar Biology P.8

1. Fishes ♥ By: Daymis Rosa & Maria Escobar Biology P.8

2. Scientific Classification • Kingdom: Animalia • Phylum: Chordata • These groups include: Jawless Fish Armoured Fish Cartilaginous Fish Ray-finned Fish Lobe Finned Fishes

3. Information….. • There is about 14,000 of discovered fish species • the first species of fish appeared on earth about 530 million years ago according to scientists. • The study of prehistoric fish is called paleoichthyology.

4. Characteristics of a Fish • A Fish is any gill-bearing aquatic vertebrate (craniates) animal that lacks limbs. Included in this group are the living hagfish, lampreys, cartilaginous and bony fish. Many other fishes as well but they have all been extinct. • Most fishes are "cold-blooded", or (ectothermic), allowing their body temperatures to vary as their environmental temperatures change. Fish can be found in nearly all aquatic environments, from high mountain streams (e.g., char and gudgeon) to the abyssal and even hadal depths of the deepest oceans (e.g., gulpers and anglerfish)

5. Oviparious Fish • The term oviparious basically refers to animals that lay eggs, without any of the embryonic development taking place inside the female animal of the certain species. This is also a process that reptiles, birds, amphibians, insects, monotremes and arachnids use to reproduce. In most fish, this means that the eggs are laid before being fully fertilized, which is a process that takes place by direct interaction with a male fish of the same species

6. Reproductive Organs • testes and ovaries, are the two main reproductive organs in any type of fish. • There are three different types of fish ovaries: *Gymnovian ovaries . * Secondary gymnovian ovaries. * cystovarian fish ovaries.

7. The Ovaries Role • Gymnovian ovaries involve the release of oocytes into the coelomic cavity, which then travel through the ostium and then enter the oviduct • Secondary gymnovian ovaries, the ova are shed into the coelom, which then results in them going direcly into the oviduct • cystovarian fish ovaries, the oocytes are directly deposited into the exterior by traveling through the oviduct.

8. The reproduction Process  • The female fish releases her eggs into the water at the same time that a male releases his milt. • The milt comes in contact with some of the eggs, and fertilization takes place. • After the eggs have been fertilized, the eggs will, either float or in some cases sink. • Once this happens it takes up to several weeks or at least a month for the fishes to hatch.

9. The Life Cycle ♥ • Eggs: Fertilized eggs develop into fish. Most eggs do not survive to maturity even under the best conditions. Threats to eggs include changes in water temperature and oxygen levels, flooding or sedimentation, predators and disease. • Larval fish: Larval fish live off a yolk sac attached to their bodies. When the yolk sac is fully absorbed the young fish are called fry. • Fry: Fry are ready to start eating on their own. Fry undergo several more developmental stages, which vary by species, as they mature into adults. Young fish are generally considered fry during their first few months. • Juvenile: The time fish spend developing from fry into reproductively mature adults varies among species. Most fish do not survive to become adults. Threats to survival

10. How do you know when it is a male and when it’s a female?.. • The only positive way to determine the sex of sexually monomorphic species, is by examination of the vent. The vent is the opening between the anus and the anal fin where the fish will excrete either eggs or sperm. The vent is also referred to as the genital papilla. • In this case the sex of this fish, is a female, you can tell by the way the vent is shaped, and the slight pink coloration. In many cases the females vent is more pinkish than a males vent, in male it is usually more round, as you can see in this picture the vent is like an oval, differentiating the male from the female.

11. Respiration The gills consist of four holobranchs that form the sides of the pharynx, Each holobranch has two hemibranchs. The hemi branch are composed of rows of long thin filament called primary lamella. The primary lamella have their surface area increased further by the secondary lamella that are semilunar folds over the dorsal and ventral surface. Exchange of gases takes place at the level of the secondary lamella. The pseudobranch lies under the dorsal operculum. This organ is a gill arch with a single row of filaments. The function of the pseudo branch is really not yet known, however scientist believe, that this structure supplies highly oxygenated blood to the optic choroid and retina and may have thermoregulation and bar receptor functions. Meaning it controls the temperature of the fishes body, and controls the blood flow of the mammals body

12. Muscular System • Most fish move by contracting paired sets of muscles on either side of the backbone. The contractions form S-shaped curves that move downwards through the body. As each curve reaches the back fin, backward force is applied to the water, and in conjunction with the fins, moves the fish forward. The fish's fins function like an airplane's flaps. The streamlined body of the fish decreases the amount of friction from the water. Since body tissue is denser than water, fish must level out the difference or they will sink. Many bony fish have an internal organ called a swim bladder that adjusts their buoyancy ( the way an object floats) through manipulation of gases.