Feather star
A feather star is a marine crinoid with multiple feathery arms used for filter feeding and movement on the sea floor.
Also known as: crinoid feather star, comatulid
How big is it?
15 cm · defined arm-tip span
Also 5.906 in
Defined arm-tip span · defined specimen
Typical recorded range: 8 cm to 30 cm.
A little perspective
Feather star vs Human brain: length comparison
The arm-tip span of a feather star is approximately equal to the front-to-back length of the human brain.
A feather star is a marine crinoid with multiple feathery arms used for filter feeding and movement on the sea floor.
The human brain is the organ that processes sensory information and coordinates thought, memory, movement and many body functions.
Both rulers start at the same zero and share one linear scale. Artwork keeps its original proportions.
Measurements, assumptions & sources +
Feather star
Defined arm-tip span: 15 cm; defined specimen; range 8 cm–30 cm.
A defined 15 cm feather star measured across its spread arm tips. Species, arm count and posture vary; this span includes the feathery arms and excludes detached cirri.
The marked defined arm-tip span is calibrated. Unmeasured illustration details are representative.
Human brain
Representative front-to-back length: 15 cm; defined specimen; range 14 cm–17 cm.
A defined adult-brain specimen 15 cm front to back and 1.4 kg. Brain size and mass vary by person; these values are comparison anchors, not health benchmarks.
Defined examples — our methodology
The marked representative front-to-back length is calibrated. Unmeasured illustration details are representative.
Use the visual comparison to explore its scale, then check the measurements and sources.
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Why this measurement?
Why we use 15 cm
We compare the arm-tip span of a feather star. This is an illustrative comparison value, not a claim that every example is the same. The recorded range is 8 cm to 30 cm.
A defined 15 cm feather star measured across its spread arm tips. Species, arm count and posture vary; this span includes the feathery arms and excludes detached cirri.
The marked horizontal span follows the measured feature, not the edges of the image. How calibrated comparisons work →
Recorded properties
Dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 15 cm | 8 cm to 30 cm | defined specimen |
Around this scale
Explore nearby values.
Compare examples with lower, similar and higher values. Each card names the measurement being compared.
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Around the same scaleEveryday objectsSmartphone15 cmLengthA smartphone is a portable electronic device that combines mobile phone functions with internet access and apps.
Nearest higher valueLiving thingsBasket star20 cmDefined arm-tip spanA basket star is a marine echinoderm related to brittle stars, with repeatedly branching arms adapted for filter feeding.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- Smithsonian Ocean — CrinoidsFeather-star anatomy and posture; the atlas uses an explicitly defined arm-tip span.
There’s always another scale
Follow your curiosity.
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