astronomy

Heliaster solaris

Heliaster solaris is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Heliaster solaris rather than just read about it. In short: Heliaster solaris commonly known as 24-rayed sunstar is an possibly extinct sea star which was known from the waters near Española Island in the Galápagos Islands. The species was endemic to the Galápagos Island group, where it appears to have been strictly restricted to the waters around the Isla Espanola.

Key takeaways

Heliaster solaris belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Heliaster solaris to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Heliaster solaris from memory before moving on to harder problems.

Reference excerpt

Heliaster solaris commonly known as 24-rayed sunstar is an possibly extinct sea star which was known from the waters near Española Island in the Galápagos Islands. The species was endemic to the Galápagos Island group, where it appears to have been strictly restricted to the waters around the Isla Espanola.

Description The body of Heliaster solaris grew up to 3 inches in diameter, and had 22 to 24 cylindrical and elongated more or less distinctly banded rays which were tapering at the ends. They were one third longer than the diameter of the body. The dorsal rows of the spines were longer and more compressed. The spines, pedicellariae, and the madreporic plate were light yellowish. It hasn’t been seen in the wild since 1983. Heliaster Solaris is poorly-understood and rarely documented species of sea star. The 24-rayed sunstar may be synonymous with another species in the Heliaster species complex that lives in the east Pacific.

Taxonomy This species was first mentioned by John Edward Gray in 1840 in the Annals and Magazine of Natural History as Asterias multiradiata and later as Heliaster multiradiatus. Due to the fact that Carl Linnaeus used the name Asterias multiradiata (current accepted name: Capillaster multiradiata) already in 1758 Gray's name became an invalid homonym. In 1920 Austin Hobart Clark published the replacement name Heliaster solaris.It was first found on San Cristóbal Island in the early 1830s.

Hunting Heliaster solaris hunted benthic invertebrates, including sea anemones, mollusks, and other echinoderms, through olfactory and tactile cues sensed by their tubefeet.

Lifecycle and Reproduction Members of the class Asteroidea (including Heliaster solaris) exhibit both asexual (regeneration and clonal) and sexual (gonochoric) means of reproduction. Life cycle: Embryos hatch into planktonic larvae and later metamorphose into pentamerous juveniles which develop into young sea stars with stubby arms. Adults usually have between 10 and 24 arms, while juveniles have only 5.

Possible extinction In the early 1980s the Galápagos Islands were affected by the El Niño-Southern Oscillation event. The increase of the water temperatures led to the turning off of the plankton production and species like the 24-rayed Sunstar or Heliaster solaris could not be found again despite a 25-year survey. And combined with the effects of an increasingly heavy tourism industry in the islands at the time, appears to have led to the specie’s decline and possible extinction.

References John Edward Gray: Mr. J. E. Gray's Synopsis of the Genera and Species of Starfish In: Annals and Magazine of Natural History Volume 6, 1840. p. 180 Austin Hobart Clark: A New Name for Heliaster multiradiatus (Gray). In: Proceedings of the Biological Society of Washington, 1920. p. 183 Graham J. Edgar et al.: El Niño, grazers and fisheries interact to greatly elevate extinction risk for Galapagos marine species In: Global Change Biology 23 October 2009 doi:10.1111/j.1365-2486.2009.02117.x

External links Photograph and news article

Illustrations

Worked examples

Example 1 — a first encounter with Heliaster solaris

Start with the simplest possible case. Write down what Heliaster solaris claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Heliaster solaris before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Heliaster solaris ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Heliaster solaris

In research: Heliaster solaris appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Heliaster solaris in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Heliaster solaris is common in secondary-school and first-year university syllabi. It links to neighbouring topics Animals described in 1920, Extinct invertebrates since 1500, Galápagos Islands coastal fauna, so understanding it makes those chapters shorter.
In everyday life: Look for Heliaster solaris outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Heliaster solaris in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Heliaster solaris means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Heliaster solaris out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Heliaster solaris in simple terms?

Why does Heliaster solaris matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Heliaster solaris?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Heliaster solaris.