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What the sources say

Purple Sea UrchinStrongylocentrotus purpuratus

Every figure, record and mechanism on the Purple Sea Urchin profile was written from a source, and this is the working table behind it: 39 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

Aquarium of the Pacific

Purple Sea Urchin. Aquarium of the Pacific.

The page saysAlaska to Baja California, Mexico
The source saysAlaska to Baja California, Mexico
The page saysThe urchin scrapes algae off rock with them.
The source saysUrchins have a special mouth, called an Aristotle’s Lantern, that helps them scrape algae off of rocksNote: Aristotle's lantern
The page saysIts body shell is called a test, and it can grow up to 10 cm (4 in) across.
The source saysTheir round bodies (called tests) can grow up to 10 centimeters (4 inches) and are covered in spines.
The page saysPincers on long stalks, called pedicellariae, help it defend itself from attackers and keep barnacles and sponges from settling on its body.
The source saysPurple 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.
The page saysTube feet help the urchin move, breathe and sense its surroundings.
The source saysThe purple sea urchin’s tube feet not only help with moving around, but they also assist with respiration and sensory input.
The page saysAt 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.
The source saysDuring low tide, purple sea urchins will ‘decorate’ themselves with bits of shell, rock and algae to protect and camouflage themselves.

Source
02

Oregon Coast Aquarium

Purple Urchin. Oregon Coast Aquarium.

The page saysMostly algae, especially giant kelp, plus dead fish, barnacles and sponges
The source saysOmnivorous; primarily algae, including bull and giant kelp, but will also eat dead fish, barnacles, and sponges.Note: stats.diet
The page saysScrapes algae with five teeth and digs hollows in rock
The source saysBesides eating, they can use these teeth to dig a depression in a rock for protection.Note: stats.superpower
The page saysIts mouth sits underneath.
The source saysSea urchins have 5 sharp teeth arranged in a circle on their underside, called an Aristotle’s Lantern.
The page saysIt holds five sharp teeth arranged in a circle, a set called Aristotle's lantern.
The source saysSea urchins have 5 sharp teeth arranged in a circle on their underside, called an Aristotle’s Lantern.
The page saysA spiny kelp grazer with five teeth in a ring, whose massed feeding fronts can strip a whole kelp forest.
The source saysthey switch to active foraging and can form dense feeding fronts that completely remove a kelp forest, leaving behind an urchin barrenNote: tagline
The page saysIt can also use them to dig a hollow in rock for protection.
The source saysBesides eating, they can use these teeth to dig a depression in a rock for protection.
The page saysSometimes an urchin grows too big to leave its hollow and is stuck there.
The source saysSometimes an urchin will grow too big to leave its depression and then is stuck thereNote: rock hollow
The page saysKelp is its favourite food.
The source saysPurple sea urchins prefer to eat kelp.
The page saysIt will also eat dead fish, barnacles and sponges.
The source saysOmnivorous; primarily algae, including bull and giant kelp, but will also eat dead fish, barnacles, and sponges.
The page saysPurple urchins have two feeding modes.
The source saysThey have 2 different feeding modesNote: the blockquote's first sentence; the lead-in joins it in the sentence split
The page saysPurple 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.
The source saysThey 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.
The page saysWhat is left is called an urchin barren.
The source sayscompletely remove a kelp forest, leaving behind an urchin barren
The page saysOnce the food is gone, the urchins' gonads shrink, and they can linger in this "zombie" state for decades.
The source saysOnce 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.
The page saysSea otters and sunflower stars eat urchins, and fewer of both have let urchin numbers jump.
The source saysA decrease in the predators of urchins, especially sea otters and sunflower stars, has enabled them to overpopulate.
The page saysThe Oregon Coast Aquarium gives an average lifespan of 20 years and says some may live as long as 70.
The source saystheir average lifespan is 20 years, though they might live as long as 70 yearsNote: lifespan
The page saysBesides sea otters and sunflower stars, the Oregon Coast Aquarium lists leather stars, California sheepshead and spiny lobsters as main predators.
The source saysSea otters, sunflower stars, leather stars, California sheepshead, spiny lobsters, and white sea urchins are their main predators.
The page saysFive teeth in a ring scrape algae off rock and dig hollows into it
The source saysBesides eating, they can use these teeth to dig a depression in a rock for protection.Note: vibe.reason

Source
03

California Sea Grant, California Seafood Profiles

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

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

Source
04

SeaLifeBase

Strongylocentrotus purpuratus. SeaLifeBase.

The page saysNot Evaluated
The source saysNot EvaluatedNote: stats.conservationStatus; no Red List assessment found by the orchestrator

Source
05

Caltech

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

The page saysIt holds more than 814 million letters of DNA and 23,300 genes.
The source saysthe sea-urchin genome contains more than 814 million letters, spelling out 23,300 genes
The page saysThe urchin and humans share an ancestor that lived over 540 million years ago.
The source saysThat ancestor lived over 540 million years ago
The page saysshare substantially more genes and biological pathways with humans than expected
The source sayssea urchins share substantially more genes and biological pathways with humans than previously suspected
The page saysScientists sequenced this urchin's genome in 2006.
The source saysCalifornia Purple Sea-Urchin Genome Sequenced by International Team November 09, 2006

Source
06

Bodnar & Coffman 2016

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

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

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.