Ch. 6 How animals stay alive Lesson 1 How animals get and digest their food

Remember… Unlike plants, algae, and some bacteria, animals cannot make their own food. Animals must get their food from other organisms by consuming, or eating, them. Animals have different ways of getting their food.

Filter feeding Many animals living in water get food though filter feeding. Filter Feeding- A way of getting food by straining it out of water. For example, sponges strain bacteria and protists out of water that passes through their body. Sponges cannot move from place to place, so filter feeding allows them to consume food without chasing it. https://www.youtube.com/watch?v=T7E1rq7zHLc

Other animals that filter feed include… Barnacles They use their legs to filter out food from water Mollusks like clams and oysters They use their gills to filter out food from water

Feeding on Fluids Some animals get their food from the fluids of plants or other animals. Aphids and Cicadas are insects that use their hard piercing mouths to drink sap from plants’ stems, roots, and leaves. Bees, butterflies, and humming birds get their food from drinking the nectar out of flowers. Leaches, Mosquitos, and Horseflies consume the blood of vertebrates, including humans.

Consuming large pieces of food Most animals consume, eat, large pieces of solid food. Some animals eat entire organisms. These animals have different body structures to capture and consume food. For example… Hydras and Jellyfish have stinging tentacles. They use their tentacles to catch small animals in the water and then bring it to their mouth.

Insects Money insects have hard mouth parts that allow them to cut up pieces of food that are small enough for them to eat. Grasshoppers, termites, and beetles use their chewing mouth parts to feed on plants. Dragonflies and praying mantises also have chewing mouth parts, but they use theirs to eat other insects.

Teeth Vertebrates are the only animals that have teeth. Mammals have teeth of different sizes and shapes. Each type of tooth has a special job. Front chisel like teeth are for cutting and tearing food. Long pointed teeth are for gripping and piercing food. Flat back teeth are for grinding and crushing food.

Picky eaters Herbivores- Are animals that only eat plants. They get all the nutrients they need from eating parts of plants. Herbivores have large flat teeth for grinding up plants Carnivores- Are animals that only eat meat from other organisms. They get all their nutrients from eating parts of other animals. Carnivores have long sharp teeth for tearing flesh. Omnivores- Are animals that eat both plants and animals to get the nutrients they need. Omnivores have both kinds of teeth. What are you? What kind of teeth do you have?

Digesting food Remember: foods contain fats, proteins, and carbohydrates. These chemicals give animals the energy they need to live. These chemicals are often too large for animal cells to use right away. So the chemicals have to be broken down before they can be used. The process of breaking down food into chemicals is called Digestion.

Breaking it down Animals digest food by secreting digestive enzymes. Secreting- To form and release, or give off. Enzyme- A substance that speeds up chemical change. Animals like sponges digest food inside their cells. But, most animals, including humans, digest their food outside their cells.

Gastrovascular Cavities Cnidarians, like hydras and jellyfish, and flatworms digest their food in a hollow space called a gastrovascular cavity. This tube only has one opening. Food enters and waste leaves the same opening. Food goes in, special cells digest food and absorb nutrients, then the what’s left over is excreted through the same opening.

Digestive tracts Animals that are more developed have a digestive tract. Digestive Tracts- A tube-like digestive space with an opening at each end. Food moves through the digestive tract one way through the body. https://www.youtube.com/watch?v=JnzwbipJuAA

The main functions of the digestive tract are… Storing food Digesting food Absorbing nutrients

Food’s path Food enters the digestive tract through the mouth. It passes down the throat into the esophagus to the stomach. In the stomach, food mixes with stomach acid and digestive enzymes. The mixture then moves through the small then large intestines. Nutrients is absorbed through the intestine walls Finally, waste is excreted through the anus.

Different digestive tracts Birds have organs called gizzards that help them break down food. They also have a crop that allows them to store food. Humans do not have these organs in their body. The stomach does the job of a gizzard and a crop.