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Red-knobbed starfish

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Red-knobbed starfish
Red-knobbed starfish.jpg
Scientific Classification
Binomial Name

Protoreaster linckii

Red-Knobbed Starrish on the Indian Ocean.
Protoreaster linckii (Blainville, 1834).jpg

The Red-Knoobbed Starfish is a species of starfish best known for its noticeable traffic-cone-like knobs are very distinguishing. They live in the Indian Ocean as well as the the eleven armed starfish . The Red-Knobbed Starfish can also be found in a few other tropical waters. Like other starfish, the Red-Knobbed Starfish can do major damage to coral reef, but this little, harmful echinoderm is crucial to the marine food chain.

Anatomy

This is the back of of a Red-Knobbed Starfish, showing the hundreds of tubed feet.

External
Each Red-Knobbed Starfish has at least five arms. Some have less and some have many more. The one truly amazing physical aspect is on its dorsal side. The Red-Knobbed Starfish has multiple red knobs throughout the body. These red knobs are connected to each other by a surfacing red cord-like,wiry material which make the starfish like a grid.[1]

On the ventral side connected to the radial canals, there are thousands of little tubed feet which act like a suction cup. These hundreds of tubed feet, allow the starfish to stick to the side of rocks, and move as it likes throughout the sea.

At the end of each arm, there is a photoreceptor eye spot. This eye spot allows the starfish to see the difference between light and dark, and detect movement of the currents of the ocean and possible preditors.[2]

Internal
The internal anatomy of the Red-knobbed Starfish is the same as all other starfish types. All starfish have two stomachs, a cardiac stomach and a pyloric stomach. The cardiac stomach is at the very center of the Red-Knobbed Starfish and helps with eating mollusks like clams and mussels. Once the Red-Knobbed Starfish has a clam in its arms, it pries the mollusks shell open and release its stomach into the shell. The stomach has very strong digestive juices that kills and liquefies the animal inside the shell. Once the mollusk is dead, the stomach sucks up the animal, brings in its stomach, and leaves the empty shell on the ocean floor. When the Red-Knobbed Starfish digests the mollusk, it goes to the anus to be expelled into the sea.[3]

Reproduction

This is a baby starfish on a thumb nail.

All starfish become sexually active at the age of 12- 14 months old. Like fish, starfish start mating during the months of May and June. Starfish reproduces sexually, but the sexes are not together. This act and the fertilization of the eggs is external. The female releases millions of eggs the size of one- two cm. in diameter into the sea while the male releases his sperm in to the sea also. The eggs and sperm meet, fertilization is complete and a blastula is formed. After a short period of time, the blastula forms a cilia for swimming around the sea. Without a head or brain, the blastula can navigate through the sea and begins to familiarize itself to its surrounding. The blastula grows bigger into a larva. The larva now has its own stomach, with the cilia as a blastula, in the stomach can inhale food. After a few months, the larva grows to be a small starfish. In this case, a Red-Knobbed Starfish.[4]

Ecology

Picture was taken in Germany in aquarium. Red-Knobbed Starfish

Most, if not all, starfish only eat mollusks. Red-Knobbed Starfish eat clams, oysters and mussels and possibly coral. In most cases, when a starfish feeds on coral, it will destroy the coral and end up killing it.[5] Also, a single starfish will eat a bed of mussels at one time. Although the starfish is a food source for many marine animals, the starfish can easily hurt parts of the marine ecosystem by eating key components.[6] It would be wise to keep it in a minimum 10 gallon tank to satisfy their spacious needs. It would also be wise to not put they in the same aquarium as coral reefs, they will eat it. On the other hand, they will not harm other starfish and fish. Not to mention they are really easy to take care of. Like other starfish, the Red- Knobbed Starfish are intolerant of sudden changes in oxygen levels and copper based medications in the water.[7]

Temperature Regulation

The Red-Knobbed Starfish lives in the Indian Ocean. Like the rest of the starfish in the world, it has a unique way to cool itself down. When a starfish is exposed to direct sunlight, its body temperature goes up. Somehow the starfish pumps itself with salt water to bring down its body temperature.

A man named Dr. Pincebourse started a study at the University of South Carolina about how starfish gained weight when exposed to sunlight. They cannot go into the ocean and go eat something because the starfish can only move in the water. So the question came up "... how can these star fish GAIN weight...?" The study showed that when a starfish is in direct sunlight its body temperature goes up rapidly, but when the starfish pumps its body with salt water, it increases the body mass and therefore, make its body temperature go up slower so that it will not die or suffer from heat stress.

Dr. Pincebourse also discovered that since the world is getting warmer, including the oceans. The starfish population may burn themselves out because the air and the oceans are going to get warmer and a starfish cannot pump cold salt water into its body.[8]

References