Invertebrates and Vertebrates
Invertebrates
Body symmetry
• Some are asymmetrical e.g. sponges
• Radially symmetrical e.g. jelly fish, starfish
• Bilaterally symmetrical e.g. snail, sea hare
Segmentation
• Body of animals divided into sections or segments
• Insects have three segments – head, thorax and abdomen
• Earthworm, marine worms
Support of the body
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Support and protection
Sponge – body is supported by jelly like material
Roundworms have thick skin
Crab and lobsters have exoskeleton
Respiratory and circulatory systems
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Respiratory system – exchange of gases
Respiration requires oxygen
E.g. gills in lobsters
Tracheae (network of tubes) in insects
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Circulatory system - transport substances
Closed circulatory system – fluid inside tubes
E.g annelids (earthworm)
Open circulatory system – fluid moves in open spaces of body
E.g. mollusks (snail)
Digestive and excretory systems
• Digestion – conversion of food from large particles/molecules to smaller
ones
• After consumption, food is digested and simpler molecules are
transported to cells
• Oxidation of food in cell (cellular respiration) produces energy
• Invertebrates have relatively simple digestive systems
Digestive and excretory systems
• Excretory system – get rid of the waste materials
• As body uses nutrients and performs reactions, wastes are
formed
• Excretory system eliminates these wastes along with excess of
water
• In some invertebrates, the digestive system removes wastes
• In others, there is a separate excretory system
Nervous system
• Nervous system – sense and respond (process information)
• Receive and send electrical signals that control functions of
the body
• Several invertebrates have a specialized area called “brain”
• Brain acts a control center
• In addition to brain, sense organs are also present
• Sense organs collect information (e.g. light)
Nervous system
Reproduction
• Budding (e.g. hydra)
• Fragmentation (e.g. planaria)
• Sexual reproduction (e.g. insects)
Development
• Development – various stages of life
• Metamorphosis – series of developmental changes in the life
cycle (insects)
• Many insects reproduce sexually and lay eggs
• The insect hatched from egg and undergo various distinct
stages of life cycle
• Metamorphosis (two types)
– Complete metamorphosis - 4 stages (Egg  Larva  Pupa  Adult)
– Incomplete metamorphosis – 3 stages (Egg  Nymph  Adult)
Development
Development
• Incomplete
metamorphosis
Vertebrates
Vertebrates
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Land, fresh water, oceans
Swim, crawl, burrow, hop, fly
Have a backbone
Head (brain, sensory organs)
Presence of cartilage (and replacement by bone during
development)
Body symmetry
• All are bilaterally symmetrical
• Head is distinct from rest of the body
• Four regions of body (dorsal, ventral, anterior, posterior)
Body coverings
• Body is covered by skin
• Protection from outer environment
• Varies in structure
– Reptiles (scales), fish (scales),
– Mucus in amphibians and fish
– Birds (feathers), mammals (fur, hair)
• Help maintaining body temperature
• Colors and patterns (camouflage and recognition)
Body coverings
Support of body
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Presence of endoskeleton
Skull, backbone, limb bones
Skull (brain), vertebrae (spinal cord)
Attachment of muscles – movement
Respiratory system
• Breathing and exchange of gases
• Two types of systems – gills (water) and lungs (land)
• Presence of blood vessels in these organs
Circulatory system
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Transport of materials
Closed circulatory system
Blood, vessels and pump (heart)
Arteries, veins and capillaries
Heart pumps blood
Oxygenation (gills/lungs)
Carbon dioxide removal
Nutrients and other substances
Waste removal (kidneys)
Digestive and excretory systems
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Digestive tract – long tube like digestive system
Direct swallowing and chewing
Food passes on to stomach (acid and enzymes)
Small intestine (absorption of nutrients , blood vessels present)
Large intestine (water absorption, undigested material is
converted to faeces)
• Nitrogenous (urea) and other wastes
• Kidneys combine wastes with water to produce urine
Digestive and excretory systems
Nervous system
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Processing information (sense and respond)
Electrical signals
Brain control center, spinal cord and nerves
Sensory organs
Sensory nerves (body to brain), motor nerves (brain to body)
Size of brain and learning
Reproduction and development
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Sexual reproduction
Fertilization - male (sperm) and female cells (egg)
Fertilized egg divides to produce multicellular stage
Differentiation of cells (specialization)
Different cells perform different function
Reproduction and development
• Amphibians and some fish – larva hatches in water, develops
into an adult organism
• Reptiles, birds and mammals do not have larval stage
• Embryo is protected by membranes
• Eggs of reptiles, birds and some mammals have a shell
• Most mammals do not lay eggs (give birth to offspring)
• Offspring develops inside the body of female individual
• Embryos of different species are similar to each other at early
stages of development
• Embryos begin to look more like the adults of their own
species as they develop
Reproduction and development
Parental care
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Number of offspring and parental care
Birds and mammals have few offspring
Feeding and protection
Parental care increases chances of surviving