2-2 Sexual Reproduction in Animals - Despite the variety amongst the many animals, they still reproduce sexually the same - meiosis produces gametes - male gamete (sperm) combines with female gamete (egg) - a zygote is produced and develops into an embryo - embryo develops by mitosis into mature offspring For success 2 things must happen - Both male and female gametes arrive in same place at same time - Zygote must receive adequate food, moisture, warmth, and protection to develop Mating Patterns in Animal Kingdom - 2 members of a population come together to combine gametes for fertilization - in some only one mating season/year (usually when offspring will hatch or be born in favourable conditions) - fish called grunion mates when tide is high, honeybee mates once in lifetime

Mating Patterns in Animal Kingdom - 2 members of a population come together to combine gametes for fertilization - in some only one mating season/year (usually when offspring will hatch or be born in favourable conditions) - fish called grunion mates when tide is high, honeybee mates once in lifetime Fertilization Patterns - occurs only if sperm meets an egg from same species - moist environment is required so gametes don’t die - egg’s cell membrane supple - sperm need water to swim 2 Patterns of Fertilization External - sperm and egg meet outside bodies - (mostly aquatic) Internal - sperm travels from male’s body into female’s body to meet the egg – development internal or external

2 Patterns of Fertilization External - sperm and egg meet outside bodies - (mostly aquatic) Internal - sperm travels from male’s body into female’s body to meet the egg – development internal or external External Fertilization - mostly water-dwelling animals Sea anemone - Adult anemones – cannot move around to mate with each other - Release eggs and sperm directly in water - rely on currents to carry gametes together - Zygotes = free-swimming, self-feeding larvae which travel distances before settling down and developing into adults Fish - female lays cluster of eggs, male releases sperm directly over eggs (spawning) Frogs - Mating – male frog embraces female who lays her eggs while male releases sperm over them - young hatch from eggs of anemones, fish, frogs and do not look like adult forms - Undergo many developmental changes to become adult forms – some live in water, others move to land

Frogs - Mating – male frog embraces female who lays her eggs while Frogs - Mating – male frog embraces female who lays her eggs while male releases sperm over them - young hatch from eggs of anemones, fish, frogs and do not look like adult forms - Undergo many developmental changes to become adult forms – some live in water, others move to land Internal Fertilization Mostly land animals – need specialized structures on male to transfer sperm directly to female Reptiles - males transfer sperm into female’s cloaca (chamber where female reproductive, urinary and digestive ducts leave body) - most reptiles lay eggs with tough, leathery shells with a fluid- filled sac surrounding the zygote – embryo Birds - few have specialized structures for transferring sperm, both males and females have cloaca - fertilization by close contact where the sperm swim from male cloaca to female cloaca - eggs laid with hard outer coverings – birds incubate, protect

Birds - few have specialized structures for transferring sperm, both Birds - few have specialized structures for transferring sperm, both males and females have cloaca - fertilization by close contact where the sperm swim from male cloaca to female cloaca - eggs laid with hard outer coverings – birds incubate, protect - most species – parents invest a great deal of energy in feeding young - some animals are born as miniature adults while others pass through different stages of development Incomplete metamorphosis (grasshoppers, crickets, frogs pass) larval form has similarities to adult Complete metamorphosis (houseflies, butterflies) -adult form does not look like earlier stages - some mothers retain and nourish young before birth which ensures additional development, protection - Mammals produce milk for nourishment of their young

Complete metamorphosis (houseflies, butterflies) -adult form does Complete metamorphosis (houseflies, butterflies) -adult form does not look like earlier stages - some mothers retain and nourish young before birth which ensures additional development, protection - Mammals produce milk for nourishment of their young Hermaphrodites - Animals that have both female and male reproductive organs Flatworms – planarians – during mating, each planarian injects sperm into a reproductive pore on other flatworm’s body - each lays fertilized eggs Earthworm – also hermaphrodite Internal fertilization – ensures sperm has moist environments to travel and increases chances that the eggs will be fertilized