Arthropods Chapter 28. Arthropods Have a segmented body. A tough exoskeleton. Jointed appendages...
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Transcript of Arthropods Chapter 28. Arthropods Have a segmented body. A tough exoskeleton. Jointed appendages...
Arthropods
Chapter 28
Arthropods
• Have a segmented body.• A tough exoskeleton.
• Jointed appendages that extend from the body wall.
• Environments they occupy are:– Sea, land, and air.The evolution of arthropods, by natural selection &
other processes, has led to fewer body segments & highly specialized appendages for feeding, movement, & other functions.
Arthropods
• Have a digestive tract, an open circulatory system, and an exoskeleton.
• Insects has a network of tracheal tubes where gas exchange takes place.
Arthropods
• Molting – arthropods outgrow their exoskeletons and will shed the entire thing and replace it with a new larger one.
• Arthropods are classified based on the number and structure of their body segments and appendages.
Arthropods
• Groups of Arthropods are:– Crustaceans – crab, shrimp, lobster, crayfish &
barnacles.– Spiders – spiders, ticks, scorpions & horseshoe
crabs.– Insects – centipedes, millipedes & insects.The easiest way to tell whether an arthropod is
an insect or a spider is to count its legs. Spider has 8, insects have 6.
Arthropods
• Insects – reason for evolutionary success is:– Ability to fly allows insects to colonize new habitats.– They may use many sense organs to respond to
stimuli.– Many have a life cycle in which the young are very
different from adults.– The body is divided into a head, thorax, and
abdomen.– Sensory hairs – insects use these hairs along with its
compound eyes to detect minute movements in its environment
Arthropods
• Difference between a Nymph and a Larva:– A nymph resembles an adult of the same
species, but a larva do not.
Echinoderms
• Spiny skin.
• Internal skeleton.
• Water vascular system.
• Suctioncuplike structures called tube feet.
• Radial symmetry.
• Examples – sea stars, sea urchins, sand dollars.
Comparing Invertebrates
• Digestion- intracellular or extracellular.
• Respiration- gills, book lungs, or tracheal tubes.
• Circulation– Open circulatory system blood is pumped through a
system of sinuses. One or more hearts.– Closed circulatory system blood is contained within
vessels that extend throughout the body. • Response (nervous system)-senses gather & process information.
• Excretion- eliminating nitrogenous wastes from the body.
• Movement & support• Reproduction- asexual & sexual
Chordates
Characteristics • A dorsal, hollow nerve cord• A notocord.• A pharyngeal pouches.• A tail that extends beyond the anus.• A vertebrate is any chordate that has a
backbone so any animal with a spinal cord must be a vertebrate.
Fish & Amphibians
FISH • Aquatic vertebrate.• Most have paired fins, scales, and gills.• Gills –structures that are important for obtaining oxygen from
water.• Heart has one atrium.
AMPHIBIANS• Lives in water as a larva & on land as an adult.• Adult breathes with lungs.• Moist skin, no scales and claws.• Example – frogs, toads, & salamanders
Reptiles & Birds
REPTILES• Dry, scaly skin.
• Lungs.
• Terrestrial eggs with several membranes.
• Can live their entire life outside of water.
• Groups–lizards, snakes, crocodiles, &turtles
• They do not excrete ammonia like most Chordates.
• Snakes are reptiles with no legs and skin unlike other reptiles.
Reptiles & Birds
BIRDS• Maintain a constant internal body temperature.• Outer covering is feathers.• Two legs that are covered with scales and are used for
walking, perching.• Front limbs are modified into wings.
• Not all birds can fly.• To distinguish bird eggs from reptile eggs, you must
test the hardness of the outer shell.• A bird’s heart ensures that oxygen-rich blood never
mixes with oxygen poor blood.
Mammals
• Have hair.
• Have the ability to nourish their young with milk. Mammary glands – found only in female mammals
• Breathe air.
• Have a 4- chambered heart and system that carries oxygen-rich blood directly from the heart to the muscles.
• Are endotherms that generate their own body heat internally.
• Water in the body is controlled by the kidneys.
Mammals
3 Main Groups of Mammals
• Monotremes – lay eggs. Ex. Platypus, anteaters.
• Marsupials – bear live young, but at a very early stage of development. Ex. Kangaroo, Koalas, Wombats
• Placental mammals – have a placenta which exchanges materials between an embryo and its mother. Ex. Mice, cats, dogs, whales, humans