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Squilla mantis
Squilla mantis
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Squilla mantis
Squilla mantis
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Stomatopoda
Family: Squillidae
Genus: Squilla
Species:
S. mantis
Binomial name
Squilla mantis
Synonyms [1]

Cancer mantis Linnaeus, 1758

Squilla mantis, also called the spot-tail mantis shrimp, is a species of mantis shrimp found in shallow coastal areas of the Mediterranean Sea and the Eastern Atlantic Ocean. It is also known as "pacchero" or "canocchia". Its abundance has led to it being the only commercially fished mantis shrimp in the Mediterranean.

Description

[edit]
Front half of S. mantis, showing the (pale-coloured) spearing raptorial claws

Individuals grow up to 200 millimetres (8 in) long.[2] This species is of the spearer type,[3] distinguished by having forelimbs formed into spiked, elongated "spears" used to capture soft-bodied prey.[4] It is generally dull brown in colouration, but has two brown eye spots, circled in white, at the base of the telson.[5] Other species – including smashers – are also sold in the aquarium trade as Squilla mantis.[6]

Distribution and habitat

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It is found around the entire coast of the Mediterranean, and in the Atlantic Ocean south from the Gulf of Cádiz to Angola, as well as around the Canary Islands, and Madeira. It has historically been recorded from Galicia, the Bay of Biscay, and the British Isles, but is not known to occur there any more.[7]

It is particularly abundant on sandy and muddy bottoms where there is significant run-off from rivers, and where the substrate is suitable for burrowing. In the Mediterranean, the outflows from the Nile, Po, Ebro and Rhône provide these conditions. Spot-tail mantis shrimp are typically encountered to depths of 150 metres (490 ft), with their highest densities commonly occurring in the 50–60 metres (160–200 ft) range. Sporadic presence occurs in deeper waters to a maximum recorded depth of 367 metres (1,204 ft).[7]

Ecology

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S. mantis digs burrows in muddy and sandy bottoms near coastlines.[2] It remains in its burrow during the day and comes out at night to hunt, and in the winter to mate. Their feeding activity is strongly linked to the night, and captive specimens tend to refuse food during the day. Adults are strongly sedentary.[7]

The alpheid shrimp Athanas amazone often lives in the burrows of S. mantis, despite being of a similar size to other shrimp which S. mantis feeds on.[8] The relationship between the two species remains unknown, although a second similar case has been reported for the species Athanas squillophilus in the burrows of Oratosquilla oratoria in Japanese waters.[9]

Spot-tail mantis shrimp are opportunistic predators and scavengers that feed on a variety of food sources determined by local availability. Common food items include other crustaceans such as crabs and decapods, mollusks such as bivalves and squid, polychaetes, and benthic fishes, alongside algae and other prey. The species has been observed following fishing boats to feed on dead animals.[7][10] S. mantis also display cannibalistic tendencies and have been recorded with remnants of conspecifics in their digestive tracts.[10] Mantis shrimp have also been recorded feeding on the egg masses of common cuttlefish.[11]

Reproduction and life cycle

[edit]

The reproductive season of S. mantis occurs over winter and spring; gonad maturity tends to peak in April in the Ligurian Sea, while in the Adriatic Sea it tends to peak between February and March. After laying, the females attach their eggs to their anterior legs using a sticky secretion produced from cement glands in their sternums. They afterwards spend spring and early summer incubating them, and do not leave their burrows or feed during this period. The eggs hatch between late spring and late summer. The larvae, termed alima, are planktonic and remain in the water column over summer and early autumn; larval numbers are highest in August, but some remain present as late as November. After passing through ten aquatic molts, the larvae settle on the sea bottom and grow to adult size over the remainder of the year; female shrimp typically spawn within their second year. While some specimens appear to grow into a third year of life, most S. mantis only spawn once.[7]

Fishery

[edit]
Squilla mantis for sale at a Catalan market

S. mantis is the only native stomatopod to be fished for on a commercial scale in the Mediterranean. Over 7,000 t is caught annually, 85% of which is caught on Italian shores of the Adriatic Sea.[12] Spain is an important secondary center of catch, while smaller fisheries exist in France, Israel, and Egypt.[7] Outside of the Mediterranean, it is consumed in Andalusia in the Gulf of Cadiz under the name of "galera".[citation needed]

Spot-tail mantis shrimp are typically caught as a valued by-catch in multi-species trawling focused on other catches such as sole and bivalves. Dedicated fishing of the species typically employs trammel nets and gillnets. Catches are generally highest in the winter, when adults are mating, and lowest in spring and early summer, when females do not leave their burrows.[7] Due to consisting chiefly of bycatch, the fishery of the species is not specifically regulated.[13]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia
Squilla mantis, commonly known as the , is a benthic stomatopod in the family Squillidae, characterized by a yellowish to brownish body up to 20 cm in length, with reddish or blue antennal peaks, dark longitudinal lines on the thoracic and abdominal segments, and a featuring distinctive yellow and dark spots. This is renowned for its , employing specialized appendages on its second thoracic limbs to deliver rapid spearing strikes at velocities up to 10 m/s, enabling it to capture elusive prey such as small , , and molluscs in under 8 ms. As a gonochoristic and oviparous , S. mantis exhibits , with females typically larger than males and comprising approximately 52% of the population (slight female bias); reproduction occurs from winter to spring, peaking in March to May, during which females brood up to 50,000 eggs in U-shaped burrows using their maxillipeds for oxygenation. Native to the and the eastern Atlantic from the to , S. mantis inhabits silty sand and sandy mud substrates in shallow coastal waters, from the down to depths of 367 m, though it is most abundant between 50 and 120 m at temperatures around 20°C. Highly territorial and sedentary, individuals excavate and maintain elaborate burrows with two openings, which serve as shelters, brooding chambers, and sites, contributing to turnover and benthic oxygenation in their . Maturity is reached at a length of 19.6–25.9 mm (varying by region and sex), with a lifespan extending several years, and the larval stage consists of planktonic zoea lasting up to three months before settlement. Ecologically, S. mantis plays a key role as a predator in soft-bottom communities, influencing prey s and nutrient cycling through its burrowing and foraging activities. Commercially significant in Mediterranean fisheries, particularly in the where it accounts for a substantial portion of trawl catches, the species supports artisanal, semi-industrial, and commercial operations, though has led to population declines in some areas. Its distinctive morphology and predatory prowess have also made it a subject of biomechanical , highlighting the evolutionary adaptations of stomatopods for high-speed locomotion and sensory integration.

Taxonomy

Classification

Squilla mantis is the binomial name for the spottail , originally described by in 1758 under the name Cancer mantis in his . Subsequent taxonomic revisions reclassified it within the genus Squilla due to its distinct morphological characteristics aligning with stomatopod features, such as the raptorial claws. The species belongs to the following taxonomic hierarchy: Kingdom Animalia, Phylum Arthropoda, Subphylum Crustacea, Class Malacostraca, Order Stomatopoda, Family Squillidae, Genus Squilla, and Species S. mantis. This placement reflects its position as a crustacean within the diverse order Stomatopoda, known for their specialized appendages. Phylogenetically, Squilla mantis is situated in the Squillidae family, which comprises spearer-type stomatopods that use barbed dactyli on their raptorial claws to impale soft-bodied prey, in contrast to the smasher types found in families like Gonodactylidae that employ club-like dactyls for striking hard shells. Molecular and morphological analyses confirm Squillidae as part of the Squilloidea superfamily, with spearers representing the ancestral condition in stomatopod evolution, from which smashing clades diverged later.

Etymology and synonyms

The genus name Squilla originates from the Latin squilla, a term for various small shrimp-like crustaceans, derived ultimately from skílla (σκιλλα), possibly referring to marine creatures or plants with similar forms. The specific epithet mantis refers to the species' forelimbs, which are enlarged and folded in a manner reminiscent of the grasping appendages of the praying mantis (Mantis religiosa). The species was first described by in 1758 under the name Cancer mantis, placing it initially in the genus Cancer for crabs, before its reassignment to Squilla as a stomatopod. Accepted synonyms include Cancer mantis Linnaeus, 1758 (superseded combination) and Squilla mantis var. major Lamarck, 1818 (junior subjective synonym, now recognized as Harpiosquilla raphidea). The species shares morphological similarities with the North American Squilla empusa Say, 1818, including traits and burrowing habits, though they are distinct taxa.

Description

Morphology

Squilla mantis possesses an elongated, segmented body typical of stomatopod crustaceans, reaching a maximum of 20 cm and commonly measuring 12 to 18 cm. The body is divided into a and , with the featuring pronounced ridges and spines that provide structural support and protection. The is flexible and includes six segments, the fifth of which bears submedian peaks with posterior spines, facilitating movement through substrates. The , the terminal abdominal plate, is flattened and equipped with a well-marked median peak, small depressions, and no tubercles, aiding in burrowing by allowing efficient sediment displacement. As a spearer-type stomatopod, the appendages, modified second maxillipeds, are specialized for prey capture and consist of a spear-like dactylus and propodus that fold together against the carpus and merus. The dactylus is armed with six spines along its edge, and its external margin is regularly convex, enabling precise impaling. Extension occurs through rapid unfolding of the dactyl, propodus, and carpus relative to the fixed merus, achieving angular velocities of approximately 20,000 s⁻¹ and linear velocities up to 10 m s⁻¹ in under 8 ms. Retraction involves initial contraction of flexor muscles to lock a sclerite against a ventral stop on the merus, followed by isometric contraction of extensor muscles to store , which is released upon flexor relaxation for swift repositioning. The and merus house the primary strike muscles, contributing to the appendage's power. Sensory structures include large, stalked compound eyes with a bilobed cornea approximately 7 mm wide. Each eye contains approximately 3,600–3,700 ommatidia, separated by a midband of two rows of enlarged ommatidia, enabling complex visual processing including polarization sensitivity and distance estimation through skewed optical axes. The eyes exhibit independent mobility across three rotational axes, providing a broad with in a 40° frontal sector. The uropods, comprising exopod, endopod, and a telson-integrated protopod, fan out from the telson base and function in propulsion during via coordinated pleopod beating. The flattened , combined with these uropods, supports burrowing adaptations by stabilizing the animal and aiding in backward excavation through .

Coloration and sexual dimorphism

Squilla mantis exhibits a subdued overall coloration, typically ranging from yellowish-brown to greenish, which aids in blending with sedimentary substrates. The body features a dark line extending along the posterior edges of thoracic segments 6 to 8 and the first five abdominal segments, along with a rectangular spot on the second abdominal segment. The is particularly distinctive, marked by yellow hues and two dark spots encircled by white rings, giving rise to the common name "spottail mantis shrimp". Variations in coloration include reddish or bluish tinges on the body's ridges or peaks, adding subtle contrast to the base tones. Juveniles tend to display paler shades compared to adults, though specific patterns remain similar. Sexual dimorphism in S. mantis is evident in size and reproductive structures. Males generally attain slightly larger maximum lengths, up to 20 cm total length, compared to approximately 18 cm in females. Males possess more pronounced abdominal pleopods, modified for transfer during .

Distribution and habitat

Geographic range

Squilla mantis is currently distributed along the eastern Atlantic coast from the (approximately 36°N) southward through the and to at around 17°S, and throughout the entire . Within the Mediterranean basin, the species exhibits highest population densities in the and the , where commercial fisheries target it intensively near river mouths and coastal zones. Historically, Squilla mantis occurred farther north in the eastern Atlantic, with records from the , Galicia, and the southern ; however, it has been extirpated from these regions, with the last confirmed sightings predating 1900 and no recent reports available. Recent surveys continue to document the species across its core range in warmer Mediterranean waters, including the central Adriatic and northern Aegean, amid regional warming trends. Ongoing regional warming may influence northern distributional limits, though no significant expansions reported as of 2025.

Environmental preferences

Squilla mantis inhabits a range of depths from littoral to sublittoral zones (0–150 m), with occasional records up to 367 m, though it is typically abundant between 120 and 150 m. In Tunisian waters, highest abundances occur shallower than 50 m, with peaks at 20–37 m due to favorable sediment stability and prey availability. This depth preference aligns with its benthic lifestyle, allowing access to nutrient-rich layers while avoiding extreme pressures. The species favors soft substrates consisting of fine sand and sandy-mud bottoms, which provide ideal conditions for burrowing in coastal bays and areas influenced by river runoff. Riverine inputs enrich these habitats with nutrients, supporting higher and prey densities that sustain S. mantis populations. Individuals construct U-shaped burrows in these sediments, with depths reaching up to 50 cm to provide shelter from predators and currents. Squilla mantis thrives in temperate to subtropical waters, preferring temperatures between 14 and 24°C, with intolerance to prolonged exposure below 10°C that restricts its northern distributional limits. levels of 30–38 ppt are optimal, reflecting its adaptation to stable marine conditions in coastal and shelf environments, though it exhibits some tolerance to variations near river mouths. These parameters ensure metabolic efficiency and , underscoring the ' niche in moderately dynamic coastal ecosystems.

Ecology and behavior

Diet and predation

Squilla mantis exhibits an opportunistic and omnivorous diet, primarily targeting soft-bodied benthic prey such as small fish, polychaete worms (annelids), mollusks, and crustaceans, while occasionally consuming , plant matter, echinoderms, and as a . The species is also cannibalistic, with conspecific remains frequently found in contents. Diet composition varies regionally and temporally due to local prey availability; for instance, crustaceans (e.g., Penaeus kerathurus and ) dominate in the Gulf of Gabes at 37.95% frequency of occurrence, whereas fish (e.g., Mullus sp. and Engraulis encrasicolus) prevail in the Gulfs of (41.93%) and Hammamet (37.72%). High vacuity indices (62.00–66.50%) indicate intermittent feeding, with many empty s observed among sampled individuals. As a spearing-type mantis shrimp, S. mantis employs predation, lurking in self-constructed burrows during the day and emerging nocturnally to hunt, when feeding intensity peaks. It uses its specialized claws—equipped with sharp, spear-like dactyls—to rapidly impale evasive, soft prey such as and , reflecting an adaptation for capturing mobile targets in soft sediments. These strikes enable precise penetration, distinguishing spearers from smasher types that employ blunt clubs for hard-shelled prey. In benthic ecosystems, S. mantis functions as a mid-level predator, facilitating energy transfer and prey while contributing to turnover through burrowing activities that enhance oxygenation. Its flexible foraging strategy allows dietary shifts in response to seasonal prey abundance, underscoring its role in maintaining community dynamics.

Symbiotic relationships and predators

Squilla mantis maintains a commensal symbiotic relationship with the alpheid Athanas amazone, in which the occupies the mantis 's for shelter. This interaction was first observed through casts of burrows in the Mediterranean, confirming the 's presence alongside the host without evidence of harm to S. mantis. The gains protection from predators by sharing the , while potential benefits to the mantis —such as grooming or alarm signaling—remain speculative due to limited on the association. The species faces predation from various marine organisms, including larger fish such as dolphinfish (Coryphaena hippurus), (Octopus vulgaris), and several demersal fishes like tub gurnards (Chelidonichthys spp.) and stargazers (Uranoscopus scaber), as well as sharks like the (Mustelus mustelus). activities like contribute to mortality. maintenance in S. mantis involves strong territorial , particularly against conspecifics, where fights over limited burrow sites can result in limb injuries or . These individuals exhibit nocturnal activity patterns, with burrow-related behaviors occurring primarily at night.

Reproduction and life cycle

Mating behaviors

The breeding season of Squilla mantis spans winter to spring, typically from to May in the Central , with peak reproductive activity occurring between March and May. This period is triggered by rising water temperatures in temperate regions, which synchronize gonadal maturation and spawning with favorable environmental conditions such as increased availability. Courtship in S. mantis and closely related Squillidae species is initiated by either and involves brief interactions centered around sites, where receptive individuals locate each other through a male search strategy rather than territorial guarding. Visual displays include antennular and spreading of the claws (meri), allowing the male to approach and mount the female for copulation, which lasts only seconds. occurs as the male inserts paired penes into the female's genital slit on the sixth thoracic sternite, transferring sperm directly via ducts to the for storage and later use during extrusion; unlike some stomatopods, spermatophores are not produced. Post-copulation, the female retreats to her to provide , attaching fertilized eggs to her pleopods beneath the and brooding them for approximately 10 weeks (about 2.5 months) without feeding. During this incubation, she uses maxillipeds to fan and oxygenate the clutch, which can contain tens of thousands of eggs, ensuring their viability until hatching into planktonic alima larvae. This prolonged brooding leaves the female vulnerable to predation and energy depletion, though specific risks of post-mating remain undocumented in S. mantis.

Larval development and growth

Following fertilization, female Squilla mantis brood their eggs within a gelatinous mass attached to the pleopods in a self-constructed , where they remain without feeding to provide and . Each typically produces a single batch of 12,000 to over 90,000 eggs, depending on body size (absolute 12,250–91,620 reported in Tunisian populations). The lasts approximately 10 weeks (about 70 days), during which the female uses her maxillipeds to oxygenate the eggs. Hatching occurs from late spring to late summer, coinciding with seasonal blooms that support larval survival. Upon hatching, the embryos emerge as planktonic alima larvae, which are free-swimming and adapted for a dispersive pelagic phase in the . These larvae undergo a 10-stage development, involving up to 9–10 molts over a duration of 2–3 months, during which they grow from initial sizes of about 5 mm in length (CL) and feed on planktonic prey. This extended larval period facilitates wide dispersal, with highest abundances observed from May to October and peaks in June at depths of 20–25 m. Settlement to the occurs in late summer to early autumn, when post-larvae (0.3–0.4 cm CL) transition to a burrowing lifestyle in soft sediments. Post-settlement juveniles rapidly construct U- or J-shaped burrows and exhibit accelerated growth, particularly during summer, reaching 15–25 mm CL by the end of the first year and 25–30 mm CL by the second year. Sexual maturity is attained in the second year class, with females maturing at approximately 20–24 mm CL (mean 23.7 mm) after 17–29 months of age. The lifespan typically spans 3 years across three age classes.

Human interactions

Commercial fishery

Squilla mantis is commercially harvested primarily as in bottom trawl fisheries across the , though it is also captured using trammel nets, gill nets, and baited traps or pots. These methods target demersal in shallow coastal waters, typically at depths of 10–60 meters, where the species is most abundant. Catches exhibit strong , with peak landings occurring in winter months (), when up to 85% of the annual yield is obtained due to increased burrow emergence and vulnerability to gear; yields drop significantly from to as adults migrate to deeper waters. Predominantly from Italian waters in the , where over 4,000 tonnes are recorded yearly, accounting for approximately 65–80% of national catches. Significant contributions also come from (around 1,200 tonnes in the late 1990s, with ongoing fisheries in ), (Gulf of Lions region), and (Gulf of Tunis and Gabes), though data for the latter countries are less comprehensive and variable. Fisheries operate without specific quotas or total allowable catches, relying on general effort controls that have proven insufficient for . As of 2023, GFCM assessments confirm in areas like GSA 17, recommending reductions in fishing mortality and recovery plans. The species holds notable economic importance in local markets, sold fresh or frozen under names like "camarón mantis" in and simply as in , where it commands prices around 3–10 euros per depending on size and season. High demand drives its value in regional trade, particularly in Adriatic ports, but stocks have shown signs of decline since the , with Italian landings fluctuating downward from 4,751 tonnes in to 4,011 tonnes in 2021, and assessments indicating in key areas like GSA 17.

Aquaculture and research

Efforts to culture Squilla mantis in aquaculture remain limited due to its aggressive behavior and specific habitat requirements. No large-scale production or documented restocking trials for Mediterranean populations have been reported. In the aquarium trade, S. mantis is occasionally kept but requires specialized care, including deep substrates for burrowing and live prey. Scientific research on S. mantis has advanced understanding of its sensory and ecological roles, with notable studies on its visual system revealing adaptations for dim light vision and photomechanical responses in the compound eye. Electrophysiological recordings demonstrate spectral sensitivities enabling detection across ultraviolet to red wavelengths, supporting polychromatic capabilities beyond simple trichromacy, though behavioral discrimination precision is lower than in vertebrates. Fishery dynamics have been modeled in key habitats like the Ebro Delta, where annual catches peak in winter (up to 700 tons), driven by fast growth (life span ~18 months in a northwestern Mediterranean population) and high natural mortality, informing stock assessments for sustainable yields. A 2024 study detailed its reproductive cycle in the Central Mediterranean, confirming a protracted spawning season from January to May (peaking March–May), with size at maturity (L50) at 25.94 mm carapace length and a female-biased sex ratio (0.524) during peak periods. Despite these advances, significant research gaps persist, particularly in symbiotic relationships—such as potential microbial or interspecies interactions in burrows—and the broader impacts of on . Limited studies indicate that rising sea temperatures may alter growth rates and , but comprehensive models integrating these effects with remain underdeveloped, especially in the .

References

  1. https://en.wiktionary.org/wiki/squilla
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