Education Update: Sex Change & Reproduction

What is the purpose of reproduction? reproduce to continue the and to have offspring.

What are the challenges of reproduction? Dealing with predators, competitors within your own species, and an unstable habitat are all challenges for reproduction.

What kinds of reproduction exist? Sexual and asexual reproduction exists.

Today we will be talking about sexual reproduction and how some animals change sex throughout their lifetimes. Specifically, we will be learning about some of the animals that go through this transition.

What makes an change sex? The most popular response is that a sex change is caused by the absence of either a male/female in a group of animals. However, other animals (like a limpet) change sex based on the presence of another animal of their same species.

Furthermore, there are two different terms used to describe sex change. • Protogyny: when an organism is born a female and changes into a male later in life. This is the most common type of sex transition.. Ex. (Family Labridae) • Protandry: when an organism is born a male and changes into a female later in life. Ex. Anemonefish

Here are some examples of animals that are either protogynous or protandrous.

California Sheephead ( pulcher)

• This is an example of a sequential . It is born one sex and later becomes another. • This animal has both male and female organs at the same time, but only one type of organs can be active at one time. It is an example of a protogynous reproductive system. • Usually a male is in charge of a harem of females. It is his job to defend female fish from other males, while he courts and mates with his harem of females. If a male disappears from the group, then the most dominant female undergoes a sex change and becomes a male. • While the picture above is of a male sheephead, this same photo would not represent a female of the same species since this animal is sexually dimorphic. The females are pink in coloration, while the males are black and red.

Clownfish (Amphiprion ocellaris)

• This is a protandrous fish that lives in communities with many males and only one female. • When the female is removed, then one of the males turns into a female. • Nemo’s Dad could have become his mom.

Slipper Snails (Crepidula fornicate)

• Slipper snails are limpets that are born male and change into females. • The limpets pile on top of one another, forming stacks. When a male is added to this group, then the limpet below it will become a female. • The females will lay about 100 eggs and are internally fertilized by the male above them on the stack. • The young planktonic larvae drift in the ocean for several weeks, then are attracted by hormones to settle on top of females. If they can not find females, then they will begin a new stack.

Napoleon Wrasse (Cheilinus undulates)

• This animal can be born as either a male or female. • When a male is no longer present, then the most dominant female will become a male. This is an example of protogeny. • These animals in the water and then their eggs float near the surface of the water till they are ready to hatch. • This fish is sexually dimorphic. Males have a big bump on their head and are bright blue in coloration. Females lack this bump and are lighter in coloration.