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Table of Contents
Starfish are echinoderms (spiny-skinned sea urchins). They are also known as sea stars and are not really fish despite the name given to them. Starfish cannot swim, and they do not use gills for breathing.
See the fact file below for more information on Seaweed, or you can download our 32-page Seaweed worksheet pack to utilize within the classroom or home environment.
Key Facts & Information
ORIGIN
- The first recorded appearance of starfish dates back around 175 million years ago, during the Late Jurassic period, making them as old as dinosaurs. Approximately 2000 known species of starfish live on the seafloor, from the tropics to the icy polar waters, across all of the world’s vast oceans.
- The Somasteroidea, which exhibit similar characteristics, were the first known starfish. On the other hand, starfish fossils are uncommon, possibly due to their hard skeletal parts that remain separate from animal decay.
- The fossil record for starfish dates back to the Ordovician period, around 450 million years ago, but it is rather sparse because starfish disintegrate after death.
- Only the animal’s ossicles and spines are highly probable to be preserved, which makes its remains difficult to find.
- The blastoids were wiped out during the two major extinction events in the late Permian and late Devonian, and only a few species of starfish survived.
- Many starfish species went extinct during these extinction events. The remaining few species then diversified rapidly over the next sixty million years during the Early and Middle Jurassic.
STARFISH ANATOMY
- Starfish are associated with sand dollars and sea urchins and are scientifically known as sea stars.
- Aside from their shape, starfish are also known for their unusual anatomy, which lacks blood and a brain but allows them to digest food outside of their body.
- These invertebrate organisms lack a backbone and no true bones at all.
- The arms of sea stars are one of their most distinguishing characteristics. Many sea stars have five arms, but some can have up to forty.
- For protection, these arms are frequently covered with spines. Large spines are found on some sea stars, such as the crown of thorns starfish.
- Starfish, unlike most sea creatures, do not have a circulatory system.
- On the other hand, they have a water vascular system, a network of canals that circulates seawater rather than blood throughout the body of a sea star.
- Clear tube feet protrude from ambulacral grooves on the starfish’s oral surface. The sea star moves by combining hydraulic pressure and adhesion.
- It functions to suck the water to fill the tube feet, causing them to extend. Muscles are used to retract the tube feet. Suckers on the ends of the tube feet were long thought to allow the starfish to grasp prey and keep moving along a substrate.
- The ability of starfish to evert their stomachs is an intriguing feature. Starfish can feed themselves by sticking their stomachs outside their bodies. Although a sea star’s mouth is relatively small, it can digest its prey outside of its body, allowing them to consume prey larger than their mouths.
- The starfish has four stages of life: gamete fertilization, the initial stage of development, metamorphosis to adulthood, asexual fertilization, and hermaphrodite species.
- Sea stars, like frogs and fish, fertilize themselves externally through a process known as spawning. In many starfish, brachiolaria is the second stage of larval development, following the bipinnaria.
- The larva quickly sinks to the bottom, trying to attach itself to the substrate with the tips of its arms first, and then with the sucker. It starts to metamorphose into the adult form once attached.
- The larval stage of starfish metamorphoses into the juvenile stage. The rest do so through morphogenesis, which occurs when species with a mesogen phase transition from embryos to juveniles. They will already be adults, but in a smaller size, and they will not be fertile.
- After a while, the juvenile starfish will have reached adult starfish and will finally be able to reproduce. As previously stated, starfish primarily have separate sexes and reproduce sexually.
- Asexual reproduction is only possible in a few species. It is unusual and usually occurs at inconvenient times, such as when a predator attacks them.
- Because starfish cannot survive outside of water, they are found in all oceans around the world, whether in cold or tropical waters.
- It is unusual to find them in freshwater. These fascinating creatures prefer the marine depths, where they cling to muddy, sandy areas between algae and rocks.
- The starfish settle easily on the seafloor, where they live completely uncomplicatedly. They most often prefer coral reefs, large algae agglomerations, and stony areas at depths of up to 6,000 meters.
- Sea star wasting (SSW) disease, also known as sea star wasting syndrome, is thought to be the most serious global threat to starfish (SSWS).
- While this is a problem in and of itself, it can also be linked to other threats, such as rising sea temperatures as a result of climate change.
- Lower oxygen levels in seawater make it more difficult for starfish to diffuse oxygen across their body surface.
- Starfish cannot obtain enough oxygen if the levels in the surrounding ocean are too low, and they will suffocate.
- One way to help prevent starfish population declines is to avoid bringing starfish home as a souvenir from the beach.
- In some cases, starfish are taken from their natural habitat and sold to tourists as souvenirs, ornaments, curios, or for display in aquariums. The preservation of starfish for decoration should be stopped as this reduces their wild population.
FEW TYPES OF STARFISH
Crown of Thorns Starfish
- The Crown of Thorns starfish is one of the world’s largest starfish. These precarious sea stars, which can grow to be nearly 1 meter long, are covered in hair-raising spikes that are venomous to both marine creatures and humans.
- A single type of starfish can chomp its way through up to 6 square meters of reef per year by using its highly flexible bodies and hundreds of tube feet to latch onto the reef’s surface.
Chocolate Chip Starfish
- The Chocolate Chip starfish can be easily distinguished by their brown cones protruding from their back. This type of starfish can grow up to 40 cm in length and comes in a wide range of colors, from light tan to red.
Sunflower starfish
- The sunflower starfish is widely recognized for its impressive arm span, which can reach 1 meter. It is the most popular starfish species in the ocean. Furthermore, it has 16β24 limbs, making sunflower starfish effective predators.
Pacific Blood starfish
- The Pacific Blood star, named after its red-orange color, is the most common starfish found along the Pacific coast of Northern America. These starfish could be found at depths of over 1,000 feet.
Royal starfish
- It was named after its opulent gold and purple hues. The Royal Starfish is found on North America’s east coast. It can dive up to 700 feet and hang out between 70 and 100 feet deep, where it can eat a lot of mollusks.
Starfish Worksheets
This fantastic bundle includes everything you need to know about Seaweed across 32 in-depth pages. These ready-to-use worksheets are perfect for teaching kids about Starfish, also known as sea stars, are marine invertebrates that come in a wide variety of sizes, shapes and colors.
Complete List of Included Worksheets
Below is a list of all the worksheets included in this document.
- Starfish Facts
- A Starfish
- Parts of a Starfish
- Starfish in Many Languages
- Starfish on Record
- Star-find the Words
- Owning a Starfish
- Under the Sea
- Draw my Starfish
- Reading Time!
- Starry Words
Frequently Asked Questions
What is a starfish?
A starfish, also known as a sea star, is a marine invertebrate with a characteristic star-shaped body.
How many legs does a starfish have?
Most starfish have five arms, but some species can have as many as 40.
What do starfish eat?
Starfish are mainly predators, feeding on clams, oysters, and other small marine animals.
How do starfish move?
Starfish move by using their tube feet, which are located on the underside of their arms.
Can starfish regrow lost limbs?
Yes, starfish have the ability to regrow lost limbs. It can take several months for a limb to fully regrow.
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Link will appear as Starfish Facts and Worksheets: https://kidskonnect.com - KidsKonnect, January 16, 2023
Use With Any Curriculum
These worksheets have been specifically designed for use with any international curriculum. You can use these worksheets as-is, or edit them using Google Slides to make them more specific to your own student ability levels and curriculum standards.