COMMON ROCKY INTERTIDAL INVERTEBRATES OF BAJA CALIFORNIA SUR SURMAR Field Guide July 2013, updated Dec. 2017 Phylum CNIDARIA (incl. anemones, corals, zoanthids) ANEMONES Bunodosoma californica (?) Common tidepool anemone. There are several similar-looking species: Anthopleura dowii, Isoaulactinia hespervolita (hespervolita means Western Flyer) ZOANTHIDS Zoanthus danae Palythoa ignota Colonial, on rocks in low Colonial, intertidal on rocks intertidal. Blue or blue-green in tidepools. Often brown or oral disk. olive-green. Phylum ANNELIDA (worms) Eurythoe complanata Spirobranchus giganteus A large amphinomid fireworm, Calcareous tube with sharp common on sandy substrate under pointy horn on rocks or coral rocks anywhere in intertidal. Sheds in low intertidal. Color is irritating spines when handled. variable -- blue, yellow, white or red. 1 Phylum MOLLUSCA (incl. limpets, snails, bivalves, cephalopods) GASTROPODS --- Limpets and limpet-like forms Lottia atrata Unidentified limpets A large limpet that can be abundant. Has a pigmented shell (Lottia stanfordiana?) pattern and rough edge (more rough than Siphonaria). Cleared feedingGASTROPODS areas are common.---Snails Siphonaria maura This pulmonate lacks gills and -, o has a lung on the right side, visible from beneath. Asymmetry on one side in larger individuals is common. Ridges and edge of shell are smoother and more delicate than in L. atrata. Smaller individuals are often abundant in lower intertidal; largest individuals are in higher intertidal, often with L. atrata. D. digueti D. saturnalis Diodora spp. Keyhole limpets, on rocks in low to mid intertidal. 2 GASTROPODS --- Predatory snails Thais speciosa is to T. biserialis but has more prominent bumps on shell and lacks the stripes/spots along the yellow aperture. Thais biserialis Predatory snail often found in cervices or nestled next to anemones in the mid to lower intertidal. Sharp white/brown striations or dots along yellow-orange aperture. Groups of snails often emerge from cracks onto barnacle beds with incoming tide. Two distinguishable forms are present in Santa Rosalia (Pta. Prieta) Neorapana tuberculata Similar to T. speciosa, but aperture is pink-orange with black splotches and small tooth on outer edge (arow). Hexaplex erythrostomus Pink murex. A large predatory snail of the low intertidal, also in pools. It is now uncommon and harvested for food and shell trade. Plicopurpura pansa A predatory muricid gastropod, found high in intertidal on rocks, usually in cracks. Knob-like protrusions in whorls on shell. When disturbed it produces a yellow-white milky sulfurous fluid that turns purple after brief exposure to air. 3 Mitra idae (CA) Morula ferruginosa Mitra (Neotirara) fultoni Mitrella ocellata guttata Smaller predator on sessile Pitted mitre shell, with white foot Small carnivorous inverts, e.g. Brachidontes. and soft parts, same habitat at collumbelid snail found in Mid to lower intertidal. Mitrella. mid intertidal pools. Conus nux Conus princeps Conus brunneus Found in mid to low intertidal, Found in mid to low intertidal, Found under or near rocks on often around green algal turf. usually in cracks or under sandy substrate in lower Active in daytime and feeds on rocks. Feeds on worms. intertidal. Feeds on fireworms, worms. The most common fond of Eurythoe. intertidal Conus. 4 GASTROPODS --- Grazing snails Littorina modesta On rocks in high Littorina and related genera intertidal. Typically Other species of small littorine snails are Littorina aspera white and lacks distinct also common, often living in dead Common in high intertidal on banding. Co-occurs barnacles – Echinolittorina albicarinata rocks and in crevices and edges with L. aspera. above were identified by DNA. of pools. Shell pattern can have a variety of forms. Nerita scabricosta Nerita funiculata. Nerita spp. Baby-tooth shell: area of Smaller and lower in the Two species of these nearly shell next to aperture looks intertidal than N. scabricosta. ubiquitous grazing snails co-occur like baby teeth or ridges on Area of shell next to aperture in the mid to high intertidal, though a comb. Smallest individuals has pimple-like protrusions they show only a narrow zone of show no sign of teeth nor rather than teeth. These can overlap. Common in cracks, under pimples (as in N. funiculata). still be resolved on the rocks, at edges of pools. Both Found in the high intertidal; smallest individuals. Can be species have a variety of shell largest individuals in similar extremely abundant. colors and patterns. habitat to Plicopurpura. 5 GASTROPODS – Vermetids (tube-dwelling snails) Serpulorbis margaritaceus White ribbed vermitid. A common solitary form which lacks an operculum Shell similar to S. margaritaceus but mantle and and has dark and light banding on the soft mantle foot dark. edge (visible on right). Smooth purple vermitid. Brown ridged vermitid Seems to have larger and White ruffled vermitid Abundant on high to middle intertidal smoother shell than ribbed Not common; these found in rocks. Dark to light tan in color and form. shaded area. often densely clumped. Several strong ridges run along shell. POLYPLACOPHORANS – Chitons Chiton virgulatus Common, found under rocks. 6 PELECYPODS --- Bivalves Brachiodontes semilaevis Brachidontes semilaevis Chama mexicana Saccostrea palmuta A small mussel, can be A small mussel, can be Rock clam. Lower valve Rock oyster. Common on rocks extremely abundant in large extremely abundant in large cemented to the rocks in mid and has flat upper valve and sheets, dense clumps adjacent sheets, dense clumps adjacent intertidal blue cast to shell. to mixed in barnacle beds. to mixed in barnacle beds. Phylum ARTHROPODA – (incl. barnacles, crabs) Grapsus grapsus Chthamalus anisopoma Tetraclita stalactifera confinis Sally Lightfoot. Mid to high Most abundant and widespread A large pink barnacle with 4 intertidal near cracks of barnacle in the Gulf. Seemingly plates, generally solitary or in exposed large rocks. variable, but Brusca treats as small groups. Mid to high Abundant and ubiquitous. GASTROPODSintertidal in exposed – Chitonsareas. one species. Clibanarius digueti. Lygia occidentalis Hermit crab. A common Rock louse. A large isopod species in central Gulf. found in high intertidal often in cervices. Central CA to upper Gulf. 7 Phylum ECHINODERMATA – (incl. sea stars, brittle stars, urchins, cucumbers) ASTEROIDS (sea stars) Pharia pyramidata Phataria unifascialis Heliaster kubiniji Single row of spines along Double row of spines on Mid and low intertidal,preys the arms. Color variable, each side of ambulacral on barnacles and brown, yellow, tan. groove. Color variable, Brachidontes, often hidden gray, reddish, blueish. in cracks. Acanthaster planci Mithrodia bradleyi Crown-of-Thorns. Well Subtidal to low intertidal. known for destructive Little known of habits. predation on coral reefs. OPHIUROIDS (brittle stars) Ophiocoma alexandri Ophiocoma aethiops Ophionereis annulata Long, slender arms. Dark, uniform color with Slender, delicate arms Common under rocks and robust arms, can be very with Commonly in in cracks. Banding on large. Under rocks. cervices in tide pools, arms distinguishes this usually only the extended species from O. aehtiops. arms visible. 8 ECHINOIDS (urchins) Echinometra vanbrunti Eucidaris thouarsii Most common urchin in Slate-pencil urchin. Under rocks Diadema or Centrostephanus Gulf, under rocks and and in crevices, often wedged in Long spined urchin in often in holes. Similar in with thick, blunt spines. tidepools. Diadema has dark- habitat and habits to purple, barbed, toxic spines. Strongylocentrotus Centrostephanus has non-toxic purpuratus in Pacific. spines that are often banded light and dark. Tripneustes depressus Low intertidal, often extremely abundant in shallow subtidal. HOLOTHUROIDS (cucumbers) Holothuria lubrica Common under rocks and in cervices, often with only branched tentacles visible. 9 .