FISHES Amanda Seijas

ORIGIN Fish are the oldest living vertebrates on Earth. They appeared about 450 million years ago and spread through almost all aquatic environments. Some species resist temperatures of over 38 ° C, others live under enormous pressure at depths of up to 10,000 meters (Abyssal Fish); while others have adapted to the icy waters with temperatures below 0 ° C.

CLASSIFICATION There are two large groups of marine fish according to the nature of their skeleton; cartilaginous fish (chondrichthyans), such as sharks and ray s bony fish (Osteictios), for example corvinas and all the rest of fish TELEOSTEOS

EXTERNAL ANATOMY

MUSCULAR SYSTEM. Muscles of the tail and trunk. to. The muscles of the tail and trunk consist of A bundle of muscle fibers called myotomes which usually have the shape of W. b The myotomes are separated by connective tissue called miosepta. Type of musculature in fish and its importance in agro-industry White Musculature: Rapid twitch (glycolytic, anaerobic), are packaged in muscle masses (miomeros), used during explosive swimming to escape. They present little myoglobin, few mitochondria and poorly vascularized. They are found in a large number of fish, usually those that do not migrate (tilapia, snapper, grouper) Tail Trunk

CARDIOVASCULAR SYSTEM. 1. Teleports present a heart with two chambers: the atrium and a ventricle 2. Oxygenated blood flows from the filaments of the gills to the organs of the head and body Fish are poikilothermic animals, however, they present some systems that allow them to regulate their temperature to some extent. For example, some tuna maintain the temperature a few degrees higher than that of the water because the red musculature heats the blood that then travels through the veins. The veins with warm blood are near the arteries that have cold blood coming from the heart. This adaptive advantage provides extra strength to the fish for fast swimming (Tunas)

DIGESTIVE SYSTEM There are herbivorous and carnivorous fish. The herbivorous fish have a long and thin intestine, while the carnivores have a short and thick intestine. 1. The esophagus of the teleosts is short and expandable to swallow large objects, it is covered with muscles 2. Most teleosts have a stomach 4. They have a pancreas that secretes enzymes in the intestine 5. In the intestine is where most of the food is absorbed. The length varies enormously depending on the type of feeding the fish has. Herbivorous fish have long and usually short carnivores. 6. The digestive system ends in the anus

RESPIRATORY SYSTEM Breathing is done through the gills. The gills are constituted by cartilaginous arches located internally in the mouth and where the gaseous exchange between blood and water takes place. 1. Water enters the gill chamber through the mouth. The teleosts can remain without moving and breathe by pumping water through their gills opening and closing the mouth 2. In the case of lungfish, they must come to the surface to breathe air. Lungfish swallow air to fill an air pocket or "lung". The lung is surrounded by veins that carry blood to be oxygenated