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Digestion in Different Animals - Natural Science 2

Learn about digestion in animals with digestive systems, animals with no digestive systems, animals with gastrovascular cavities, and animals with digestive tracts. Understand the process of digestion and how animals obtain nutrients from food.

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Digestion in Different Animals - Natural Science 2

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  1. UNIT2 The nutrition function DIGESTION IN DIFFERENT ANIMALS Natural Science 2. Secondary Education

  2. UNIT2 Digestion in different animals DIGESTION ANIMALS WITH A DIGESTIVE SYSTEM ANIMALS WITH NO DIGESTIVE SYSTEM WITH GASTROVASCULAR CAVITIES WITH DIGESTIVE TRACTS like RUMINANTS SNAILS BIRDS Click on each box to find out more Natural Science 2. Secondary Education

  3. UNIT2 Digestion in different animals Natural Science. Secondary Education, Year 2 What is digestion? • Digestion is the process by which animals transform food into smaller components to obtain nutrients from it. Go back to the Start menu Natural Science 2. Secondary Education

  4. UNIT2 Digestion in different animals Animals with no digestive system • Sponges do not have a digestive system. • They absorb water through their pores. • Inside their bodies, specialised cells catch the food particles in the water, and digest them in the cytoplasm. A cell specialised to catch nutrients from the water How watermoves througha sponge Go back to the Start menu Natural Science 2. Secondary Education

  5. UNIT2 Digestion in different animals Animals with digestive systems • In almost all animals (with the exception of sponges), digestion is carried out by a digestive system. • It is separated into three stages: • Food is crushed by mechanical means. The molecules of nutrients are broken down through chemical processes. • Nutrients are absorbed and carried to the cells. • The materials that cannot be used are eliminated. Go back to the Start menu Natural Science 2. Secondary Education

  6. UNIT2 Digestion in different animals Animals with gastrovascular cavities • Cnidarians and platyhelminthes. • Their gastrovascular cavities are bag-shaped and are sometimes branched. • They have only one opening, which is used both to ingest food and to eliminate waste. • Digestion takes place inside the cavity. The cells lining the cavity walls absorb nutrients. Gastrovascular cavity Opening The gastrovascularcavity of a jellyfish Go back to the Start menu Natural Science 2. Secondary Education

  7. UNIT2 Digestion in different animals Animals with digestive tracts • A digestive tract is a long tube with an opening for food to go in (mouth) and another opening for indigestible material to go out (anus). • The simplest digestive tracts, like those found in annelids, have parts that specialise in grinding food, but they do not have digestive glands. Mouth Gizzard (this grinds up food) Anus The digestive tractof an annelid Natural Science 2. Secondary Education

  8. UNIT2 Digestion in different animals Animals with digestive tracts • The most complex digestive tracts, like those found in molluscs, arthropods and vertebrates, have specialised parts and digestive glands that produce substances which break down the molecules of nutrients. Small intestine Largeintestine Oesophagus The digestive tractof a ruminant Ru Mouth Re O A Anus Stomach: Ru: rumen Re: reticulum O: omasum A: abomasum Digestiveglands: Pancreas Liver Go back to the Start menu Natural Science 2. Secondary Education

  9. UNIT2 Digestion in different animals Digestion in a snail Digestion begins with the snail ingesting food with a sort of toothed tongue called the radula. Food then passes to the mouth, where it mixes with saliva. The short oesophagus transports the food to the stomach. Although the salivary glands surround the stomach, the saliva is released in the mouth. From the stomach, food passes to the spiral-shaped intestine, and is expelled through the anus which is surprisingly close to the snail’s head. Stomach Salivaryglands Anus Intestine Mouth Radula Go back to the Start menu Natural Science 2. Secondary Education

  10. UNIT2 Digestion in different animals Digestion in a ruminant The animal ingests food without chewing and it passes to the rumen. Inside the rumen, microorganisms begin to digest the food. Parts of the food get sent back to the animal’s mouth to be chewed. This is calling chewing cud, or ruminating. The chewed food is swallowed again, but this time it passes to the reticulum, the omasum and the abomasum, where digestion is completed. The food passes to the intestine, where nutrients are absorbed and faeces is formed. 1 3 4 5 2 Go back to the Start menu Natural Science 2. Secondary Education

  11. UNIT2 Digestion in different animals Digestion in a bird Food passes from the mouth to the oesophagus, where there is a pouch called a crop. This is where food is moistened and softened to facilitate digestion. Sometimes birds regurgitate this softened food for their young. Food then passes to the stomach, which is made up of a proventriculus, which separates digestive fluids, and a gizzard, which has a very muscular wall to finish grinding the food. From there, the food goes to the intestine, where it is mixed with fluids in the liver and the pancreas. The intestine ends in the cloaca. Proventriculus Crop Gizzard Cloaca Go back to the Start menu Natural Science 2. Secondary Education

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