Key to Class Holothuroidea

Taken primarily from  Kozloff, 1987, 1996  (Copyright 1987, 1996, University of Washington Press.  Used in this web page by permission of University of Washington Press)

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1a	Upper surface of body with numerous large, fleshy, pointed projections; buccal tentacles moplike; length commonly greater than 25 cm	2
1b	Upper surface of body without fleshy, pointed projections; buccal tentacles bushy, pinnately branched, or unbranched, but not moplike; length rarely exceeding 25 cm	3
2a	Color usually reddish brown or orange-brown, sometimes mottled; length up to about 50 cm; primarily subtidal, but also low intertidal	Parastichopus californicus
2b	Color reddish orange with small white papillae and rust-colored patches; length up to about 38 cm; strictly subtidal	Parastichopus leukothele
3a	Without tube feet other than the buccal tentacles; buccal tentacles either unbranched or pinnately branched	4
3b	With tube feet on at least part of the general body surface; buccal tentacles bushy	7
4a	Buccal tentacles unbranched, fingerlike; body wall thick, without anchor-shaped ossicles that project externally; aboral end of the body tapering to a "tail"	5
4b	Buccal tentacles pinnately branched; body wall thin, with anchor-shaped ossicles that project externally (these ossicles are microscopic, but they engage one's skin when the animal is handled); body slender, but not tapering to a "tail"	6
5a	Body elongated, with a long tail; color generally pinkish, purplish, or silvery gray; intertidal or subtidal, in rather clean sand	Paracaudina chilensis
5b	Body stout, with a short tail; color mostly reddish brown or reddish purple; subtidal, in mud	Molpadia intermedia
6a	Usually with 12 (sometimes 11 or 13) buccal tentacles; body surface with raised papillae; color almost uniformly pale pink; average diameter of oocytes about 400 micrometers; primarily intertidal in muddy sand and gravel	Leptosynapta clarki
6b	Usually with 10 (sometimes 9 or 11) buccal tentacles; body surface without raised papillae; color white with dark red spots (more spots on the upper surface and near the anterior end than elsewhere); shallow subtidal	Leptosynapta transgressor
7a	Lower surface of body a flattened "sole" with 3 double rows of tube feet; upper surface covered by large calcareous plates	8
7b	Lower surface of body not flattened to form a "sole"; upper surface not covered by calcareous plates	10
8a	Calcareous plates on upper surface with small nodules readily visible at 10x magnification (caution: the nodules, to which the sandpaperlike texture of the plates is due, break off readily if scraped); greatest diameter of plates not often exceeding 5 mm	9
8b	Calcareous plates on upper surface without small nodules; greatest diameter of plates in larger specimens (at least 5 cm long) sometimes exceeding 1 cm, and usually at least 5 mm in smaller specimens (general color reddish brown; tentacles red; common shallow water species, and sometimes intertidal)	Psolus chitonoides
9a	Length up to 3 cm; general color pinkish or lavender; greatest diameter of calcareous plates about 3 mm (common subtidal species)	Psolidium bidiscum (Psolidium bullatum in key)
9b	Length up to 6 cm; general color not pinkish or lavender; greatest diameter of calcareous plates in larger specimens (3-6 cm long) about 5 mm	Psolus squamatus
10a	Length commonly 20-25 cm, but cometimes attaining 35 cm; general body color usually reddish brown, sometimes with a purplish tinge, but the buccal tentacles bright orange or orange-brown, and the introvert about the same color; common intertidal and subtidal species, usually in crevices and between rocks	Cucumaria miniata
10b	Length rarely exceeding 20 cm (Lambert, 26 cm) (and in most species, other than Havelockia benti and Cucumaria fallax, not often exceeding 10 cm); general body color not reddish brown, and the buccal tentacles and introvert not bright orange or orange-brown (they may, however, be pale orange or pale brown)	11
11a	General body color (the buccal tentacles and introvert may be different) white, cream, yellowish, pale orange, pinkish, brown, or tan, but neither dark nor conspicuously speckled with dark pigment (Havelockia benti, whose color ranges from pale orange to brown, often has small dots of brown pigment, but these contribute to a nearly uniform coloration rather than to conspicuous speckles)	12
11b	Body either dark (often blackish) or conspicuously speckled with dark pigment	19
12a	Body tapered at both ends (the posterior end may look like a tail) and curved at least slightly (sometimes the body is nearly U-shaped)	13
12b	Body not obviously tapered at either end and not curved	15
13a	Skin with the texture of fine sandpaper; perforated ossicles of body wall triangular to oval (length up to 10 cm, but commonly 5 or 6 cm)	Pentamera pseudocalcigera
13b	Skin rather smooth to the touch, not at all like sandpaper; perforated ossicles of body wall diamond-shaped, circular, or star-shaped	14
14a	Body plump, decidedly curved, and with the posterior portion tapering quickly to a nipplelike tail; perforated ossicles of body wall circular to star-shaped and with an obvious central spine	Pentamera populifera
14b	Body not especially plump, and only slightly curved, the posterior portion not tapering so quickly that there is a tail; most ossicles of the body wall diamond-shaped, with 4 large perforations in the central portion (there are also a few smaller, circular plates that have minute spinelets on one surface)	Pentamera lissoplaca
15a	Tube feet not restricted to the ambulacra; general body color light brown, but sometimes pale orange; length up to 20 cm	Havelockia benti
15b	Tube feet restricted to the ambulacra (although the rows of tube feet may be irregular); general body color white, yellowish, pale orange, pale brown, or tan; length not often exceeding 10 cm (except in Cucumaria fallax, whose length may reach 15 cm)	16
16a	General body color pale brown, tan, or yellowish; length up to 15 cm (Lambert, 26 cm); body slimy when the animal is alive (introvert white or whitish; buccal tentacles faintly pinkish or yellowish; subtidal, mostly under rocks in cobble)	Cucumaria pallida
16b	General body color white to pale orange (not brown or tan); length rarely exceeding 10 cm; body not slimy	17
17a	Length not often more than 3 cm; perforated ossicles of body wall with numerous knobs and spines on the one surface (rare subtidal species)	Pentamera trachyplaca
17b	Length commonly 5-10 cm; perforated ossicles of body wall without knobs and spines (common intertidal and subtidal species)	18
18a	Tube feet slender (when the animal is relaxed), their length usually less than the width of the interambulacral areas; color nearly pure white; body wall thin; animal often covering itself with pieces of algae, bits of shell, and other foreign material	Eupentacta pseudoquinquesemita
18b	Tube feet rather stout (when animal is relaxed), their length usually greater than the width of the interambulacral areas; color white to pale yelllow or pale orange; body wall tough; animal not often covering itself with foreign material	Eupentacta quinquesemita
19a	Prevailing color whitish or yellowish, with purple, brown, or black speckles	Cucumaria piperata
19b	Color almost uniformly grayish, grayish brown, or blackish (albinistic specimens occur, however)	20
20a	With many tube feet between the ambulacra; ossicles of body wall button-shaped, with 4 holes; length up to about 5 cm; subtidal (Identified in 1996 key as Cucumaria lubrica)	Pseudocnus curatus
20b	With few if any tube feet between the ambulacra; ossicles of body wall neither button-shaped nor with 4 holes; length up to about 2.5 cm; intertidal, and usually in beds of Mytilus californianus	Cucumaria pseudocurata