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Genre：Video
Author：BrainPOP
Size：390KB
Date Published：November 20, 2006
Transcript:
The title shot shows a sponge sitting on an ocean floor.
Text reads: The Mysteries of Life with Tim and Moby.
The scene shifts to show a robot, Moby, sitting in a bathtub. His arms are moving, and there are sounds of water splashing. A door opens and a boy, Tim, carrying a piece of paper, calls in.
TIM: Hey, where are all the sponges?
Tim reads from a typed letter.
TIM: Dear Tim and Moby, What are underwater sponges? From, Walker. Moby found these saltwater sponges when he was snorkeling yesterday, but sponges can live in fresh water too.
An animation shows three sponges on an ocean floor. Coral can be seen growing in the background, and bubbles can be seen in the water. This scene is replaced by a drawing showing a portion of an organizational chart showing animal hierarchies. At the top of the chart is an oval with the title “Animal Kingdom.” A vertical line leads down from this oval to a horizontal line. The left side of the line is labeled “invertebrates,” and the right side is labeled “vertebrates.” The right branch continues offscreen to the right. The left branch has a line going down to a long bar that extends offscreen both to the left and to the right. The on-screen portion of the bar has lines descending to ovals labeled with assorted phyla. Next to the name of each phylum is a small symbol in the shape of a typical animal in that phylum.
TIM: Sponges are simple invertebrate animals—they don’t have a backbone.
The animation pans around the chart and eventually zooms in on the oval labeled “Porifera phylum.” The symbol in this oval has the shape of a sponge.
TIM: Adult sponges are sessile, which means they live their whole lives attached to one place.
An animation shows a sponge sitting at a fixed spot on the edge of a rock formation. Rocks and coral are in the foreground. A caption reads “sessile.”
TIM: A sponge’s body is made from two layers of cells. And sponges are filter feeders: they collect food from water that flows through their bodies.
An insert on the left side of the screen shows a close-up of a sponge with moving arrows depicting water flowing through the sponge. The arrows are black when they enter the sponge and blue when they exit.
TIM: Microscopic organisms and oxygen are carried through pores to the central cavity of the sponge.
A close-up of the sponge is shown. A thick black arrow is shown entering on one side and leaving on the other side.
TIM: Little hair-like flagella extend from the collar cells and keep water moving through the sponge.
An orange, roughly circular shape appears in the center of the outline of the cell. It is surrounded by arms—what Tim calls “hair-like flagella—extending from the circular shape. A caption reads: “flagella.”
TIM: Other specialized cells digest food, carry nutrients to all parts of the sponge, and remove waste.
An arrow is shown moving through the cell from right to left. The arrow is purple when it enters the cell. While passing through the cell, the shade of the arrow changes until it is light blue upon exiting the sponge. The view changes to an animation of Tim standing next to Moby. Tim is wearing a white tee shirt with an illustration of a sponge. The three blue lights on Moby’s chest flash as he speaks.
MOBY: Beep.
TIM: Yep, human cells perform those same tasks. Not many animals eat sponges, but hard glass-like spicules and a tough elastic spongin skeleton will make any predator think twice.
An animation appears showing a large sponge underwater. Fish are swimming by and ignoring the sponge. The screen splits into two close-ups of the sponge. The left side of the frame shows spiny pyramids jutting out of the sponge. The caption reads “spicules.” The right frame shows a close-up of the outer layer of the sponge, showing many oval indentations. The caption reads “spongin.” The view is replaced with a close-up of Tim speaking. He holds up a bath sponge.
TIM: The spongin skeleton, incidentally, is the part people can use as a bath sponge after the animal dies.
The scene shifts to one showing three sponges in a row on the ocean floor. Coral can be seen growing in the background.
TIM: Sponges reproduce both sexually and asexually. In asexual reproduction, a bud will grow on the side of a parent sponge.
A tiny identical sponge can be seen emerging and growing from the large sponge. A caption reads: “asexual reproduction.”
TIM: Eventually, that bud develops into a small sponge, breaks off, floats away, and anchors itself somewhere else.
The bud breaks off and floats off the screen.
TIM: New sponges also grow when a sponge is cut or broken into pieces.
A new scene shows a sponge on the ocean floor split into six pieces. A disinterested fish swims by.
The view switches back to Tim and Moby.
TIM: Most sponges that reproduce sexually can produce both eggs and sperm, two types of gametes, or reproductive cells. Usually, sponges of the same species will release both sperm and eggs into the water on the same day. As Tim says “gametes,” a caption appears in order to emphasize the word.
An animation shows two sponges resting on the ocean floor. Both emit clouds that come together in the center of the frame.
TIM: The water current mixes the gametes from many sponges, and then fertilization happens.
The view zooms in on the mixture of the two clouds. That scene fades away and is replaced by Tim standing next to Moby.
MOBY: Beep.
Tim continues to speak.
TIM: It is like pollination. Geez, you’re on the ball today. Fertilized eggs grow into larvae that swim around ’til they find a good place to attach themselves.
An insert appears showing an egg gently landing on a bumpy surface. A caption reads: “larva.”
The view shifts back to Tim and Moby. Tim is entering a bathroom carrying a sponge and approaching Moby from the rear. Moby points into the bathtub.
MOBY: Beep.
A view of the bathtub is shown. It is filled with water. Floating in the water are a large number of sponges of various sizes, shapes, and colors.
TIM: Aw, man …
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