Reproduction in Animals

• Animals known as invertebrates undergo an asexual form of reproduction called

  _______ in which new organism (ex. Hydra) form as outgrowths on the body of a parent.

  budding
• _______ occurs when one adult animal divides into two almost equal-sized

  individuals, this is mostly seen among Planaria worms.

  Binary fission
• ________occurs when body

  parts of an individual break off into smaller pieces, those smalls parts then regenerate which

  eventually grow into the adult size.

  Fragmentation
• ____________occurs when eggs develop into embryos without fertilization which

  is observed in some species of bees, wasps, and ants. In honeybees, the males (drones) are

  haploid fertile adults that develop from parthenogenesis.

  Parthenogenesis
• Sexual reproduction in animals requires the mating of the male and female. In some

  animals however, finding a mate becomes very difficult. To solve this problem, some species

  evolved to adapt, and the result is ________ in which an individual possesses both

  the male and female reproductive systems and is common among stationary or sessile animals

  like barnacles, clams, burrowing animals, and many parasites like tapeworms. Some

  hermaphrodites, like the sea slugs, can both receive and give sperms during mating, while

  other species like corals can self-fertilize.

  hermaphroditism
• When the male dies, a

  particular female in the population can undergo a _______transforming it into a male.

  More females in the population ensure more offspring for the continuity of the species

  population.

  sex reversal
• These reproductive cycles are controlled by hormones (produced

  by ________ or sex organs that also store the gametes) which are also regulated by

  environmental conditions (some are seasonal) that are important in ensuring the survival of

  offspring.

  gonads
• Females have the most complex reproductive cycles that include _______, the

  release of mature eggs, occurs in the middle of the cycle which can last 15 or more days (in

  humans, 28 days).

  ovulation
• _______ can also last for many months (9 months from conception in

  humans), the longest of which is that of the elephants which can be approximately 22 months.

  Pregnancy
• _______-The females lay the undeveloped eggs. The eggs may have been fertilized

  before release, as in birds and some reptiles, or are to be fertilized externally, as in

  amphibians and many lower forms.

  Oviparity
• ________-In sharks (and other animals), the embryos develop inside eggs that are

  retained within the mother's body until they are ready to hatch.

  Ovoviviparity
• ________-The embryo develops within the female’s body and are delivered through live

  birth, ex. humans.

  Viviparity