Animal Deveolpment (3/12/26)

Asexual Reproduction

One parent; offspring are genetically identical

Ex: sponges, sea stars, and insects

Sexual reproduction

Two parents; offspring have genetic variation

Ex: most mammals, birds, reptiles, fish

Fission

The process where a sexually immature polyp undergoes asexual reproduction by splitting into multiple pieces

Budding

A new organism develops from an outgrowth or “bud” on the parent organism

Fragmentation

A new individual can grow from a detached arm that includes a portion of central disc

Parthenogenesis

An embryo develops from an unfertilized egg without any sperm

Hermaphroditism

An organism that can produce both eggs & sperm

Simultaneous hermaphrodites

Both male & female reproductive organs that are functional at the same time

Ex: snails, slugs, earthworms

Sequential hermaphrodites

Born with one sex & change to the other later in life

Ex: Clownfish

Chromosomal

Establishes an individual’s biological sex based on the presence or absence of specific chromosomes

Environmental

Environmental factors (temp, hormones) influence the development of an individual’s biological sex

Ex: turtles, alligatores, crocs, lizards

Internal Fertilization

When sperm fertilizes an egg cell inside the body

External Fertilization

When sperm & egg cells are released outside the body & mix, almost always in water

Ex: Nearly all fish (spawning), frogs

Viviparous

The Embryo develops internally & receives nourishment directly until birth

Oviparous

The fertilized egg is laid outside the body, & the embryo develops using a yolk sac

Yolk Sac

rich in protein & fat

Ovoviviparous

Fertilized egg is retained inside the body, but the embryo develops using a yolk sac - not nourishment from the parent

Eggs hatch inside body or immediatly

Fertilization

When gametes (egg & sperm) fuse to from zygote

Cleavage

Rapid cell division from a single-celled zygote to a multicellular organism

Blastula

A hallow ball of cells formed after cleavage

Gastrulation

blastula cells rearranged to from 3 layers of cells

Germ layers

3 layers will differentiate into organ systems

Endoderm, Mesoderm, Ectoderm

Organogenesis

Production & development of organs

Cellular differentation

Less specialized cell to become a more specialized cell type

Endoderm

Gut & many internal organs

Mesoderm

Muscle cells & connective tissue

Ectoderm

Nervous system & the skin

Epithelial cells

Cover the body’s external surface & libes internal organs & cavities

Connective

Supports & binds other tissues together

Muscle

Responsible for movemnt & contraction

1. Skeletal: attached to bones

2. Smooth: stomach, intestines

3. Cardiac: heart walls

Nervous

Transmits electrical impulses & coordinates body function

Compound of neurons & suporting cells (glia)

Tissue Regeneration

Process of replacing or restoring lost or damaged tissue to its original form & function

1. De-differentation

Mature cells revert to a less specialized state

Proliferation

Rapid increase in number