---
title: "What the sources say about the Purple Sea Urchin | AnimalTracks.wiki"
description: "39 claims from the Purple Sea Urchin profile, each beside the words of the source that backs it."
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# What the sources say about the Purple Sea Urchin (*Strongylocentrotus purpuratus*)

> 39 claims from the Purple Sea Urchin profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Purple Sea Urchin](https://animaltracks.wiki/animals/purple-sea-urchin/)

## Purple Sea Urchin. Aquarium of the Pacific.

https://www.aquariumofpacific.org/onlinelearningcenter/species/purple_sea_urchin

| The page says | The source says |
| :--- | :--- |
| Alaska to Baja California, Mexico | Alaska to Baja California, Mexico |
| The urchin scrapes algae off rock with them. | Urchins have a special mouth, called an Aristotle’s Lantern, that helps them scrape algae off of rocks (note: Aristotle's lantern) |
| Its body shell is called a test, and it can grow up to 10 cm (4 in) across. | Their round bodies (called tests) can grow up to 10 centimeters (4 inches) and are covered in spines. |
| Pincers on long stalks, called pedicellariae, help it defend itself from attackers and keep barnacles and sponges from settling on its body. | Purple Sea Urchins also have pedicellariae, which are long stalks with a pincher at the end. These pinchers help the urchin defend itself from attackers and keep sponges and barnacles from growing on their body. |
| Tube feet help the urchin move, breathe and sense its surroundings. | The purple sea urchin’s tube feet not only help with moving around, but they also assist with respiration and sensory input. |
| At low tide, when the water has pulled back, it sticks pieces of shell, rock and algae onto itself. The Aquarium of the Pacific says this protects and camouflages it. | During low tide, purple sea urchins will ‘decorate’ themselves with bits of shell, rock and algae to protect and camouflage themselves. |

## Purple Urchin. Oregon Coast Aquarium.

https://aquarium.org/?p=21127

| The page says | The source says |
| :--- | :--- |
| Mostly algae, especially giant kelp, plus dead fish, barnacles and sponges | Omnivorous; primarily algae, including bull and giant kelp, but will also eat dead fish, barnacles, and sponges. (note: stats.diet) |
| Scrapes algae with five teeth and digs hollows in rock | Besides eating, they can use these teeth to dig a depression in a rock for protection. (note: stats.superpower) |
| Its mouth sits underneath. | Sea urchins have 5 sharp teeth arranged in a circle on their underside, called an Aristotle’s Lantern. |
| It holds five sharp teeth arranged in a circle, a set called Aristotle's lantern. | Sea urchins have 5 sharp teeth arranged in a circle on their underside, called an Aristotle’s Lantern. |
| A spiny kelp grazer with five teeth in a ring, whose massed feeding fronts can strip a whole kelp forest. | they switch to active foraging and can form dense feeding fronts that completely remove a kelp forest, leaving behind an urchin barren (note: tagline) |
| It can also use them to dig a hollow in rock for protection. | Besides eating, they can use these teeth to dig a depression in a rock for protection. |
| Sometimes an urchin grows too big to leave its hollow and is stuck there. | Sometimes an urchin will grow too big to leave its depression and then is stuck there (note: rock hollow) |
| Kelp is its favourite food. | Purple sea urchins prefer to eat kelp. |
| It will also eat dead fish, barnacles and sponges. | Omnivorous; primarily algae, including bull and giant kelp, but will also eat dead fish, barnacles, and sponges. |
| Purple urchins have two feeding modes. | They have 2 different feeding modes (note: the blockquote's first sentence; the lead-in joins it in the sentence split) |
| Purple urchins have two feeding modes. When drifting kelp is plentiful, they sit and catch it. When the supply drops, they switch to active foraging and form dense feeding fronts that can remove a kelp forest completely. | They have 2 different feeding modes: they can act as sedentary feeders catching drifting kelp, but when this supply drops off, they switch to active foraging and can form dense feeding fronts that completely remove a kelp forest, leaving behind an urchin barren. |
| What is left is called an urchin barren. | completely remove a kelp forest, leaving behind an urchin barren |
| Once the food is gone, the urchins' gonads shrink, and they can linger in this "zombie" state for decades. | Once the forest/food is gone, the gonads of the urchin shrink, so they lose their nutritional value for any potential predators, and may exist in this zombie state for decades. |
| Sea otters and sunflower stars eat urchins, and fewer of both have let urchin numbers jump. | A decrease in the predators of urchins, especially sea otters and sunflower stars, has enabled them to overpopulate. |
| The Oregon Coast Aquarium gives an average lifespan of 20 years and says some may live as long as 70. | their average lifespan is 20 years, though they might live as long as 70 years (note: lifespan) |
| Besides sea otters and sunflower stars, the Oregon Coast Aquarium lists leather stars, California sheepshead and spiny lobsters as main predators. | Sea otters, sunflower stars, leather stars, California sheepshead, spiny lobsters, and white sea urchins are their main predators. |
| Five teeth in a ring scrape algae off rock and dig hollows into it | Besides eating, they can use these teeth to dig a depression in a rock for protection. (note: vibe.reason) |

## Purple Sea Urchin. California Sea Grant, California Seafood Profiles.

https://caseagrant.ucsd.edu/seafood-profiles/purple-sea-urchin

| The page says | The source says |
| :--- | :--- |
| The purple sea urchin is a round, spiny animal. | Key identifying features for this sea urchin are purple spines that protrude from a round body. |
| Rocky shores and kelp beds from Alaska to Baja California, Mexico, as deep as 160 m | Rocky intertidal and kelp beds, founds in depths of up to 160 meters (525 ft). (note: stats.habitat; range) |
| California Sea Grant gives a typical size of 5 to 10 cm wide and 4 cm tall. | Ranges in size from 5-10 cm (2-4 in) wide by 4 cm (1.6 in) tall. |
| Young urchins are mostly pale green, and their spines darken to purple as they mature. | Adolescents have mostly pale green spines that darken to purple as they mature. |
| It likes rocky shores and kelp beds, from the intertidal zone as deep as 160 m (525 ft). | Rocky intertidal and kelp beds, founds in depths of up to 160 meters (525 ft). |
| At temperatures above 22.8°C (73°F), more of them die. | Water temperatures in excess of 22.8°C (73° F) increase mortality. |
| California Sea Grant reports that some areas, such as northern California, have enough urchins to suppress kelp. | populations in some areas, such as Northern California, large enough to be suppressing kelp |
| Yes, the egg or sperm organs (gonads) are the part eaten. | Gonads from females and males (that produce roe or milt). |
| California harvested the species for food in the 1990s, but the catch is now mostly harvested for scientific research. | Harvested as food in the 1990s, this species is now mostly harvested for scientific research. |

## Strongylocentrotus purpuratus. SeaLifeBase.

https://www.sealifebase.se/summary/SpeciesSummary.php?id=49326

| The page says | The source says |
| :--- | :--- |
| Not Evaluated | Not Evaluated (note: stats.conservationStatus; no Red List assessment found by the orchestrator) |

## California Purple Sea Urchin Genome Sequenced by International Team. Caltech.

https://www.caltech.edu/news/california-purple-sea-urchin-genome-sequenced-international-team-1213

| The page says | The source says |
| :--- | :--- |
| It holds more than 814 million letters of DNA and 23,300 genes. | the sea-urchin genome contains more than 814 million letters, spelling out 23,300 genes |
| The urchin and humans share an ancestor that lived over 540 million years ago. | That ancestor lived over 540 million years ago |
| share substantially more genes and biological pathways with humans than expected | sea urchins share substantially more genes and biological pathways with humans than previously suspected |
| Scientists sequenced this urchin's genome in 2006. | California Purple Sea-Urchin Genome Sequenced by International Team November 09, 2006 |

## Bodnar & Coffman (2016). Maintenance of somatic tissue regeneration with age in short‐ and long‐lived species of sea urchins. Aging Cell.

https://doi.org/10.1111/acel.12487

| The page says | The source says |
| :--- | :--- |
| A 2016 aging study, citing earlier work, puts the maximum life expectancy in the wild at more than 50 years. | that of Strongylocentrotus purpuratus is estimated to be more than 50 years (note: current source for lifespan) |
| In that study, old urchins regrew snipped-off spines and tube feet as quickly as young ones. | the rate of regrowth of both spines and tube feet was maintained with age in L. variegatus and S. purpuratus |