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All-Female Species

Middle school learnscience.org

Name Date

Predict

In some species of lizards, snakes, fish and salamanders, every adult is female. There are zero males. Could a species with no males keep having babies for thousands of years?

Circle one. Yes / No

Why?

Watch

  1. Some species are all female and they still make babiesyoutube.com/shorts/usPB5PGeb0E

Word of the day

Unisexual (yoo-nih-SEK-shoo-ul). Having only one sex. Every unisexual animal with a backbone that scientists have found is all female.

Word partComes fromMeaning
uni-Latin ūnusone
-sexualLatin sexussex
  • A unicycle has one wheel.
  • In music, voices singing in unison share a single sound. The word comes from Latin for “of a single sound.”

Questions

  1. Whiptail lizards make babies by parthenogenesis, making babies without fertilization. In the video, Raven says whiptail babies are near copies of their mom. Why are whiptail babies near copies of their mom? And what’s one good thing about a species where every adult is female?

    Hint. Think about who adds DNA to a baby. Then think about how many adults in the species can lay eggs.

  2. The Amazon molly is a fish. She needs sperm from a male of a different species to start her eggs. But her babies almost never get any of his DNA. Does the Amazon molly still count as an all-female species? Give your reason.

    Hint. Every Amazon molly is female, and her babies are almost always copies of their mom. How often does the male’s DNA end up in the babies?

  3. Whiptails don’t need males. But sometimes two female whiptails act like they are mating. How could you test if mating-like behavior between two females helps whiptails have babies?

    Hint. Picture two groups of lizards. What would you change between the groups? What would you count?

  4. The Brahminy blind snake spread around the world in the soil of potted plants. How does having no males help the Brahminy blind snake start a new group in a new place?

    Hint. If no male is needed, how many snakes does it take to start a new group?

Exit ticket

In the video, Raven says some all-female fish need sperm from a male of another species to start their eggs. She also says two female whiptails act out mating-like behavior, even though whiptails need no male. What does the male’s sperm do for an all-female fish’s egg? And why do two female whiptails act out mating?

Hint. For the fish, think about whose DNA ends up in her babies. For the whiptails, think about what the behavior helps their bodies do.

Sources