Oligocottus snyderi

Geographic Range

Oligocottus snyderi , the fluffy sculpin, is a marine species and is only found along the Pacific Coast of the United States, Canada and Mexico, where it is native. It is a common species found throughout the temperate, rocky intertidal zone from as far south as Baja California and northern Mexico, to as far north as Sitka, Alaska (Freeman 1985). It is often numerically dominant in subtidal, low intertidal, and mid-intertidal pools in Central California (Freeman 1985). While it is thought that O. snyderi moves between intertidal pools (Yoshiyama 1992), this species does not appear to migrate long distances. No reports of the introduction of this fish to other regions have been found in the literature.

• Biogeographic Regions
• nearctic nearctic
  • native native
• pacific ocean pacific ocean
  • native native

Habitat

Oligocottus snyderi is most commonly found in temperate, rocky, subtidal and low intertidal pools, though it is also found frequently in mid-intertidal pools. Due to its numerical domination in “the rocky fish assemblage”, it is suggested that O. snyderi , “plays an important role in the functional organization of the intertidal community” (Grossman 1984). Oligocottus snyderi is rarely found in high intertidal pools, and it is believed that it almost universally prefers the stability and cooler temperatures of the low intertidal pools (Freeman 1985, Nakamura 1976b). Experiments have shown that O. snyderi strongly prefers low tidal pools with vegetation such as eelgrass, Phyllospadix schouleri , and algae such as Laminaria , Iridia , Porphyra , and Corallina (Nakamura 1976a). However, because the fluffy sculpin does not inhabit high tide pools that have this macrophytic cover, it is believed that latitudinal placement (and/or temperature) plays a more significant role than vegetation in habitat choice (Nakamura 1976a). Based upon experimental evidence (Nakamura 1976a), it is believed that the most highly preferred habitat of O. snyderi is low to mid-intertidal pools with eelgrass and a sand substrate. Its second preference was shown to be a rock-sand zone, and its least preferred habitat is the open, sand-only zone. Fluffy sculpins are capable of aerial breathing for extended periods (hours) of time, during which their respiration rate seems to remain stable (Yoshiyama 1994). It is thought that this stable air breathing may be a response to the preference of O. snyderi for vegetated cover, which may expose it to frequent reductions in low-oxygen waters at night, due to respiration by the covering plants (Yoshiyama 1994).

Fluffy sculpins are believed to be stenothermal (Moring 1981), and it is suggested that this requirement for a stable temperature range restricts this species to low intertidal pools, and explains the dominance of this species in tidal pools from Central California to British Columbia, where the temperature range is less extreme than in areas further to the north or south. Laboratory tests have demonstrated that O. snyderi has less tolerance for long-term increases in heat exposure than does its close relative Oligocottus maculosus , which resides is the high intertidal zone (Nakamura 1976b). This evidence supports the observed preference of O. snyderi for the lower, more stable pools and may support hypotheses that O. snyderi is more successful in northerly climates. Interestingly, Zamzow found that fish, including O. snyderi , in low intertidal pools have fewer ultraviolet processing compounds than species that occupy the high intertidal zone. The reduction in these compounds may be associated with the preference of O. snyderi for more vegetative cover and lower tidal pools (Zamzow 2003).

The depth range of O. snyderi is considered less than 0 meters because it inhabits the intertidal and subtidal zones (FishBase), which are by nature fairly shallow. However, within the context of a particular pool, it appears that O. snyderi is not restricted in terms of depth. Experiments that imposed simulated tidal fluctuations on individuals demonstrated that, even during tidal changes, fluffy sculpins did not alter their vertical position (Nakamura 1976a). However, fluffy sculpins have also been described as a “bottom dwelling carnivores” (Nakamura 1976b), implying that in a natural setting, O. snyderi may tend to move along the bottom of pools under the cover of vegetation to feed.

• Habitat Regions
• temperate temperate
• saltwater or marine saltwater or marine

• Aquatic Biomes
• benthic benthic
• temporary pools
• coastal coastal

• Other Habitat Features
• intertidal or littoral intertidal or littoral

Physical Description

Oligocottus snyderi is a small cottid, approximately 8.9 cm in length (Oregon State University, 2003b), though it has also been described as ranging from 13 to 101 mm in length (Moring, 1981), and as having a mean length of 47 to 48 mm (Yoshiyama, 1980). It is hypothesized that fluffy sculpins in northern ranges grow to be larger due to more ideal environmental conditions (Freeman, 1985). Oligocottus snyderi has no scales, but rather has a ‘fluffy flesh’ behind the dorsal fin for which it gets its name (Oregon State University, 2003b). Oligocottus snyderi has 7 to 9 dorsal spines, 17 to 20 dorsal soft rays, no anal spines, 12 to 15 anal soft rays, and a rounded caudal fin (FishBase, 2004). A particularly interesting physical trait of O. snyderi is the prehensile first anal ray found on males, which is used to clasp females during copulation (Morris, 1956). Fluffy sculpins have been found to live from 1 to 2+ years, depending on study location sites. They were found in one study to have an average body mass of 8.0 plus or minus 0.3 grams (Yoshiyama, 1994). Because they have no scales, they are more difficult to age (must use a vertebral aging method), and relatively little is known of their early life history (Nakamura, 1976b).

Oligocottus snyderi is close morphologically to Oligocottus maculosus , the tidepool sculpin, which is abundant in the high intertidal zone of the east Pacific shore. However, O. maculosus is distinguishable by its larger size (Yoshiyama, 1980), its habitation of the high intertidal zone, by its color and pigmentation, and by the number and rows of cirri on the lateral body surface (Nakamura 1976b). Though these two species share similar morphology and their habitats slightly overlap vertically, they do not appear to compete for energy or space resources, due to a distinct partitioning of resources. However, this resource partitioning does suggest that competition for resources between these two species drove their evolution in the past, which may have resulted in their current “niche complementarity” (Yoshiyama, 1980).

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• ornamentation ornamentation

Development

It has been stated that the life histories of intertidal fishes, and especially cottids, are not well-understood (Freeman, 1985). In general, it is suggested that fluffy sculpins mature early and are short-lived (Freeman, 1985). It is also thought that the life history and development of Oligocottus snyderi is intricately connected to its fluctuating tidal environment. It has been demonstrated that the growth of O. snyderi is influenced by seasonal fluctuations in nutrients caused by upwellings along the East Pacific Coast (Freeman, 1985). Instantaneous growth rates in fluffy sculpins were shown to be highest during the nutrient rich upwellings (April to August) and lowest during the low productivity Ocean-Davidson current period (October to February) (Freeman, 1985).

Fluffy sculpins develop through larval, post larval, juvenile and adult stages. Eggs are fertilized internally (Morris, 1956), are deposited on rocks, and are guarded by the males (Oregon State University, 2003b). Further details regarding egg deposition and hatching were not found in the literature. The diagnostic characteristics of the larval stage in O. snyderi are a “patch of parietal spines; 10 to 12 spines that develop along preopercular margin; and 8 to 10 accessory spines that form anteriorly at the bases of the preopercular spines” (FishBase, 2004). Oligocottus snyderi larvae are distinguished from O. maculosus larvae by a “bubble of skin interior to the origin of the dorsal finfold that is unpigmented and less obvious” (FishBase, 2004). Additionally, the larval head and nape are lightly pigmented (FishBase, 2004). It is believed that larval metamorphosis is timed to coincide with the nutrient rich upwellings that occur along the East Pacific Coast from April to August (Freeman, 1985). There is little information on the post-larval stages of O. snyderi and it is not known how post-larvae “settle” in particular pools, but the data suggests that temperature plays a factor in the choice of pools, and that an internal threshold temperature is determined in the larval or post-larval stage (Nakamura 1976b). It is believed that juveniles mature and are capable of spawning within their first year (Freeman, 1985), and the data suggests that males exceed females in growth during their second year (Freeman, 1985; Morris 1956).

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

According to Grossman, there is no substantial reproductive data on intertidal fishes or cottids (Grossman, 1984). Morris (1956), in studying the anatomy of the male O. snyderi clasping anal spine did observe mating in a laboratory setting. He stated that, “no definite patterns of display or courtship were apparent and copulation took place in an atmosphere of carefree promiscuity” (Morris, 1956). Of course, this behavior could be solely attributed to the artificial setting. Oligocottus snyderi reproduces using internal fertilization, and the males have a developed penis and clasping anal ray that assist in this process (Morris, 1956). The first anal ray on the males is set apart and is prehensile. The male “bends this ray anterolaterally around the female” and uses it to hold the two fish together as they mate. This ray can bend to the right or left and thus male fluffy sculpins are able to approach females from either side. It is suggested that clasper flexing is stimulated by visual or touch stimuli (Morris, 1956). Morris witnessed mating taking place away from the substrate and lasting 4 to 5 seconds, again in a laboratory setting. Internally fertilized eggs are laid on rocks and are guarded by the males (Oregon State University, 2003b).

It is hypothesized that most fluffy sculpins are large enough to spawn within their first year, but it is not clear how many survive to do so (Freeman, 1985). The literature suggests that the reproductive cycle in O. snyderi females is strongly coordinated with the nutrient upwelling and downwelling cycles that occur along the East Pacific Coast (Freeman, 1985). Freeman found that ovarian recrudescence occurs in females during the downwelling period (October to February) during which time the water is not as nutrient rich and instantaneous growth rates are slow, but during which time females are observed to eat more than males. It is assumed that this excess energy is used in egg production (Freeman, 1985). In Freeman’s study at Dillon Beach, CA, strong seasonal fluctuations in the feeding and reproduction of fluffy sculpins were observed. Due to the fact that females contain vitellogenic oocytes from October through May, Freeman hypothesizes that females spawn more than once per year and do so during the winter and spring. Following this hypothesis, larval metamorphosis, and possibly recruitment, could be timed to occur with the seasonal nutrient upwellings (Freeman, 1985). It is also hypothesized that reproductive success rates may improve as males age because of their increased body and clasper size (Freeman, 1985).

A detailed study of the follicular development in female fluffy sculpins has been conducted by Grossman (1984), who found that follicular development is consistent with that of other oviparous teleosts. Two to four clutches were observed in females between October and May, and Grossman hypothesizes that the female breeding period may last from six months (November to April) to eight months (October to May); rapid follicular enlargement was seen in September. The fact that clutches found in females during this time were in differing stages of development is evidence of asynchronous reproduction and the multiple spawning events also described by Freeman.

• Key Reproductive Features
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

Oligocottus snyderi males guard the eggs deposited by females.

• Parental Investment
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • protecting
    • male

Lifespan/Longevity

The lifespan and longevity of O. snyderi appears to be strongly affected by its environment. While one study in the wild found only two age classes of fluffy sculpin present, 0+ and 1+ (Freeman, 1985), another study found individuals of 2+ years (Moring, 1981). In captivity, O. snyderi has survived for more than two years (Yoshiyama 1992). Because they have no scales, they are more difficult to age (must use a vertebral aging method), and relatively little is known of their early life history (Nakamura, 1976b).

Freeman hypothesized that the shorter lifespan (1.5 years) and the small size of the fluffy sculpins he studied might be the result of the strong seasonal fluctuations at his field site. He suggests that the further north the species is located (within its ideal range from Central California to British Columbia) the longer its lifespan will be due to reduced temperature fluctuation. There is also reduced exposure to ultraviolet radiation further north, which could contribute to the increased lifespan of more northerly populations, though there is not concrete evidence for this (Zamzow, 2003).

Behavior

As in many other intertidal fishes, a homing mechanism has been documented in O. snyderi , and it is suggested that fluffy sculpins occupy home ranges of more than one pool (Yoshiyama, 1992). It is suggested that the fluctuating intertidal environment demands that fishes, such as O. snyderi be able to find and recognize safe spots (Yoshiyama, 1992). Fluffy sculpins have been observed to return to their home pools even if it is necessary to cross exposed, ‘inhospitable’ habitat to do so (Yoshiyama, 1992). They have also returned to home pools even if transplanted into other equally suitable habitats (Yoshiyama, 1992). However, for O. snyderi it seems that “site fidelity and homing success depend upon local topographic characteristics and other environmental factors (e.g. exposure to wave action, frequency of habitat perturbations)” (Yoshiyama, 1992). For example, evidence suggests that O. snyderi may lose the drive to return home if unsuccessful for a certain period of time (Yoshiyama, 1992). Also, it is not clear whether fluffy sculpins simply “wander” back home, or if they rely upon distinct visual or olfactory cues (Yoshiyama, 1992). In general, larger individuals seem to be more successful at homing than are smaller individuals. It is not clear how young may use homing to move through the intertidal zone, though the absence of dead young in unsuitable habitats (such as the high intertidal pools) suggests that pools are non-randomly selected, and that site fidelity is established in the post-larval stage, possibly by temperature cues (Yoshiyama, 1992). Temperature does seem to be an overarching factor in habitat selection by O. snyderi (Freeman, 1985; Moring, 1981; Grossman, 1984; Nakamura, 1976a, b; Yoshiyama, 1992).

In regards to interspecies relationships, O. snyderi displays no competitive or aggressive behavior in the presence of the closely related tidepool sculpin, Oligocottus maculosus . The spatial habitat of the two species overlaps slightly in the mid-intertidal range. However, they eat different food and prefer different habitats. When occupying a tank together, they show no signs of aggression (Nakamura, 1976a).

Perhaps most interesting behaviorally is the ability of O. snyderi to breathe aerially. The literature states that only a few marine fish families (Stichaeida, Pholididae, and Cottidae) are air breathing (Yoshiyama and Cech, 1994). However, several temperate zone rocky intertidal fish are able to breathe aerially (Yoshiyama and Cech, 1994), presumably due to their need to adapt to the constant change in tidally influenced environments. Both O. snyderi and O. maculosus can breathe for extended periods of time out of water (hours). O. snyderi is a particularly interesting air breather because its respiratory rates in air and in water are similar and stable, whereas the closely related O. maculosus has a greatly increased respiration rate out of water (Yoshiyama and Cech, 1994). This seems counterintuitive, as O. snyderi occupies the more stable subtidal and low intertidal zones, which do not fluctuate in water level or temperature as greatly as do the high intertidal zones in which O. maculosus lives. However, the strong affinity that O. snyderi has for vegetative cover indicates that it may inhabitat pools that experience low oxygen levels at night, when photosynthetic rates are low (Yoshiyama and Cech, 1994). Low oxygen levels, in turn, may demand an increase in air breathing. No information in the literature was found detailing the nocturnal behavior of O. snyderi .

• Key Behaviors
• natatorial natatorial
• motile motile

Home Range

The home range of O. snyderi is hypothesized to encompass multiple intertidal pools (Yoshiyama and Cech, 1994).

Communication and Perception

The literature suggests that fluffy sculpins do communicate with mates, as is evident by males’ use of their claspers during intercourse (Morris, 1956). The extent to which communication occurs during mating is unclear, but males use their claspers to hold onto females during the internal fertilization process. While the literature does not suggest how mates find each other, it is assumed that they use visual perception channels to some extent.

Communication and perception between O. snyderi and its physical surroundings is evident in the homing ability of the species. It appears that O. snyderi uses pool temperature to determine whether it is in its appropriate pool range (Nakamura, 1976). However, it would seem that O. snyderi must utilize homing indicators in addition to temperature, as the species is able to distinguish between its home pool and other pools that are similar in temperature and overall habitat quality (Yoshiyama, 1992). It is suggested in the literature that visual and olfactory perception may assist the fluffy sculpins in homing (Yoshiyama, 1992). Furthermore, larger individuals were significantly better at homing than were smaller individuals (Yoshiyama, 1992), implying that visual and olfactory sensory abilities may increase with body mass. It is interesting to note that O. snyderi has been observed to lose its homing drive after repeated failed homing attempts (Yoshiyama, 1992), indicating that sensory systems, whether olfactory or visual, may adjust to stimuli from new pools given time.

In terms of finding and catching prey, O. snyderi has been observed directly charging prey in a laboratory setting (Yoshiyama, 1980). It is assumed that visual perception of prey plays an important role, though it is possible that additional perception/communication channels are utilized.

• Communication Channels
• visual visual
• tactile tactile

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

The food habits of Oligocottus snyderi are well-documented (Freeman, 1985; Yoshiyama, 1980). The diet of O. snyderi consists primarily of gammarid amphipods and polychaetes, though diet shifts occur in conjunction with nutrient upwellings. A greater diversity of prey are captured and eaten during nutrient upwellings (Freeman. 1985). Oligocottus snyderi appears to be the dominant consumer of gammarid amphipods in the subtidal and low intertidal zones (Freeman, 1985). Analysis of stomach contents has revealed that larger fluffy sculpin individuals prey upon shrimp and crabs, and eat a greater diversity of food in general (Freeman, 1985). Freeman's study found that gammarids compose a larger percentage of the female diet than the male diet, though alternate studies did not report this. Additionally, Freeman found that males ate a greater diversity of food.

In a laboratory setting, O. snyderi captured prey by charging it directly, whereas O. maculosus was more covert in its hunting (Yoshiyama, 1980). Yoshiyama hypothesizes that this results in O. snyderi consuming fewer shrimp than does O. maculosus (Yoshiyama, 1980). In turn, he suggests that the development of these slightly different predatory strategies and dietary compositions contributes to the ability of these two species to live in such close proximity to one another without intense competition.

• Primary Diet
• carnivore carnivore
  • eats non-insect arthropods
  • vermivore

• Animal Foods
• aquatic or marine worms
• aquatic crustaceans
• other marine invertebrates

Predation

While anecdotal evidence of predation of O. snyderi by birds and larger fish was found, no documentation of specific predators was found in the literature.

Ecosystem Roles

While the numerical dominance of O. snyderi in subitdal and low to mid-intertidal pools indicates that it plays a signifant role in the funtioning of these highly fluctuating and specialized ecosystems, no studies investigating the specific role of fluffy sculpins in these ecosystems were found in the literature.

Economic Importance for Humans: Positive

It has been suggested that O. snyderi may be a suitable and/or desirable ornamental fish (Oregon State University, 2003a), but no detailed evidence has been found in the literature.

Oligocottus snyderi is intrinsically beneficial to humans because it contributes to the biodiversity and ecosystem functioning of the intertidal zone, which in turn supports the highly productive neritic zone of the Pacific Coast of North America. This is a highly productive ecological region that supports critical fisheries and the larger oceanic ecosystem as a whole.

Economic Importance for Humans: Negative

There are no known adverse effects of O. snyderi on humans.

Conservation Status

Oligocottus snyderi is not listed on any of the conservation status sites.

Other Comments

Oligocottus snyderi Greeley was first described in 1898, in Jordan and Evermann’s, The Fishes of North and Middle America: a descriptive catalogue of the species of fish-like vertebrates found in the waters of North America north of the Isthmus of Panama (FishBase, 2004).

The author noted that multiple unpublished doctoral dissertations were referenced in the literature. These sources were unaccessible to the author, but they may provide additional and/or more current information on the life history and behavior of Oligocottus snyderi .

Additional Links

Encyclopedia of Life

Contributors

George Hammond (editor), Animal Diversity Web.

Lauren Theodore (author), University of Michigan-Ann Arbor, William Fink (editor, instructor), University of Michigan-Ann Arbor.

References

FishBase, 2004. "Oligocottus snyderi (species summary)" (On-line). Accessed October 22, 2004 at http://www.fishbase.org/Summary/SpeciesSummary.cfm?ID=4131&genusname=Oligocottus&speciesname=snyderi .

Freeman, M., N. Neally, G. Grossman. 1985. Aspects of the life history of the fluffy sculpin, Oligocottus snyderi . Fishery Bulletin , 83 (4): 645-656.

Grossman, G., V. de Vlaming. 1984. Reproductive ecology of an intertidal sculpin, Oligocottus snyderi. Journal of Fish Biology , 25: 231-240.

Moring, J. 1981. Seasonal Changes in a Population of the Fluffy Sculpin Oligocottus snyderi from Trinidad Bay, California, USA. California Fish and Game , 67(4): 250-253.

Morris, R. 1956. Clasping mechanism of the cottid fish, Oligocottus snyderi Greeley. Pacific Science , 10: 314-317.

Nakamura, R. 1976. Experimental Assessment of Factors Influencing Micro Habitat Selection by Two Tide Pool Fishes, Oligocottus maculosus and Oligocottus snyderi. Marine Biology , 37(1): 97-104.

Nakamura, R. 1976. Temperature and the Vertical Distribution of Two Tide Pool Fishes, Oligocottus maculosus and Oligocottus snyderi. Copeia , (1): 143-152.

Oregon State University, 2003. "Fluffy Sculpin" (On-line). Accessed October 22, 2004 at http://hmsc.oregonstate.edu/projects/msap/PS/masterlist/fish/fluffysculpin.html .

Oregon State University, 2003. "Potential Ornamental Aquaculture Species" (On-line). Accessed October 22, 2004 at http://hmsc.oregonstate.edu/projects/msap/PS/topornamentals.html .

Oregon State University, 1998. "The Tide Pool Page : Sculpins" (On-line). Accessed October 22, 2004 at http://hmsc.oregonstate.edu/projects/rocky/sculpin.html .

University of Washington Fish Collection, 1996. "Family Cottidae, Sculpins" (On-line). Accessed October 22, 2004 at http://artedi.fish.washington.edu/FishKey/cott.html .

Yoshiyama, R., J. Cech. 1994. Aerial respiration by rocky intertidal fishes of California and Oregon. Copeia , (1): 153-158.

Yoshiyama, R., M. Philippart, T. Moore, J. Jordan, C. Coon, L. Schalk, C. Valpey, I. Tosques. 1992. Homing behavior and site fidelity in intertidal sculpins. Journal of Experimental Marine Biology and Ecology , 160: 115-130.

Yoshiyama, R. 1980. Food habits of three species of rocky intertidal sculpins. Copeia , (3): 515-525.

Zamzow, J. 2003. Ultraviolet-absorbing compounds in the mucus of temperate Pacific tidepool sculpins: variation over local and geographic scales. Marine Ecology Progress Series , 263: 169-175.