Sepia pharaonis

Geographic Range

Pharaoh cuttlefish ( Sepia pharaonis ) have a large geographic range, reaching as far east as Zanzibar, as far west as Australia, and as far north as Japan. They span the Indian Ocean, the Persian Gulf, the Red Sea, the Arabian Sea, and the Andaman Sea.

• Biogeographic Regions
• palearctic palearctic
  • native native
• oriental oriental
  • native native
• ethiopian ethiopian
  • native native
• australian australian
  • native native
• indian ocean
  • native native
• pacific ocean pacific ocean
  • native native
• mediterranean sea
  • native native

Habitat

Pharaoh cuttlefish live in fairly shallow waters, ranging as deep as 130 m. They tend to rise up in the water column at night to hunt for crustaceans and small fish. The depth ranges in which they congregate depend on their geographic location. In the Andaman Sea and the Gulf of Thailand they are found in waters about 10 to 40 m deep. This ranges are also affected by the seasons, as they are migratory. During mating season, off the coast of Hong Kong, they are found at depths of 40 to 80 m.

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

• Aquatic Biomes
• benthic benthic
• reef reef
• coastal coastal

Physical Description

Pharaoh cuttlefish can grow to about 80 cm in mantle length, with males larger than the females on average. The largest recorded male was 80 cm long and weighed about 5 kg, while the maximum record for females was 50 cm long, weighing 2 kg. Both of these individuals were found in the Persian gulf.

Pharaoh cuttlefish share the same color changing mechanism as other cuttlefish species, and can even change the texture of their skin. The color changing mechanism of pharaoh cuttlefish is controlled by muscular rings that expand and contract around color-filled sacs called chromophores. The resting color for pharaoh cuttlefish is generally a solid color that alternates between white and dark brown, but they can also present a white-and-brown mottled color with a brown circle in the center.

Pharaoh cuttlefish, like other cuttlefish, have large eyes with protective cornea layers and sharp beaks located at the base of their mantles. Their internal organs, both digestive and reproductive, are located in their mantles. Their mantles also contain an internal shell, or cuttlebone. Cuttlebones are oblong in shape with a rounded end on the posterior side and a point on the anterior side. Cuttlebones are porous and allow cuttlefish to control their buoyancy by changing the amount of gas present within their cuttlebones. Pharaoh cuttlefish are dorsoventrally flattened with long, oval-shaped bodies that are bordered by narrow fins. These narrow fins extend the entire mantle until they reach the posterior end, where they do not connect. The ventral tentacles of pharaoh cuttlefish tend to be longer and broader when compared to their retractible arms. These tentacles also contain suckers that are in a 2 to 4 series.

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

• Sexual Dimorphism
• sexes alike
• male larger
• sexes colored or patterned differently

Development

Mature male pharaoh cuttlefish reach mantle lengths of about 7 cm, whereas females reach about 8.6cm. Note that maximum lengths differ by geographic region, because pharaoh cuttlefish are a species complex. This means that they may not be one species, but rather a group of closely related species that are too difficult to distinguish.

Young pharaoh cuttlefish are fairly well developed at birth and even exhibit most adult behaviors at mantle lengths of around 8 mm (a hatchling size). The weight increase for pharaoh cuttlefish is low within the first 60 days of life, but in the 5th and 6th month of life they gain weight exponentially. Pharaoh cuttlefish reach sexual maturity within 4 to 5 months of its hatching.

Reproduction

There are two distinct sexes, male and female, in pharaoh cuttlefish. They tend to mate in the spring and summer, where they migrate to shallower waters. They perform elaborate courtship routines that involve males changing their normal mottled color to a zebra-striped pattern in order to attract females. Males flash their zebra-striped pattern to notify other males that they are also males, while females remain mottled in color. Competition between males can be intense, and in some cases may even become violent. After competing, one male remains with the female to mate. In most cases this is the larger male. The victorious male will then stroke the female between her eyes, and will changes his color back to the normal mottled pattern, notifying his readiness to mate. If another male tries to interrupt mating, the defending male will again flash the zebra-striped pattern, but only on the side facing the other male so he does not startle the female.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Pharaoh cuttlefish mate through internal fertilization, where males insert spermatophores into the buccal membrane of a female. They do this by using a modified arm called a "hectocotylus" that continuously breaks open the spermatophores ensuring they attach to the buccal membrane. In most males, approximately 140 spermatophores are attached to the female in a single mating episode. After mating is complete, females lay eggs 1 to 2 cm long and covered in ink to darken them. Both males and females can mate several times, but after spawning both sexes will die.

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

Pharaoh cuttlefish are precocial, meaning that offspring are well developed and independent when born. This means that there is no further parental involvement of the offspring other than the initial protection of the eggs by placing them in a relatively safe environment.

• Parental Investment
• no parental involvement
• pre-fertilization
  • provisioning
  • protecting
    • female

Lifespan/Longevity

Average lifespan for pharaoh cuttlefish is about 240 days, or 8 months. They die after they have completed spawning.

Behavior

Pharaoh cuttlefish actively hunt at night hide during the day; this goes for hatchlings and adults. Young also hatch at night. Pharaoh cuttlefish are fairly solitary creatures that only come together to mate. Prey recognition is innate in hatchlings. By the time they reach mantle lengths of about 8 mm, hatchlings present behaviors common of adults. These common behaviors include locomotion, prey capture, ejection of ink, and sudden changes in color due to environmental factors or emotions.

Pharaoh cuttlefish can propel themselves rapidly through the water using jet propulsion. They do this by filling their mantle cavity with water and then quickly expelling the water through their siphon. This behavior can be used to either escape from predators or quickly ambush unsuspecting prey. The use of their siphons for a quick escape can also be paired with an ejection of ink in order to disorientate potential predators. Pharaoh cuttlefish specifically have demonstrated a unique arm-flapping behavior when approaching their prey. They raise their first pair of arms while wrinkling and darkening them. Simultaneously, they bend their second and third pair of arms as if they are on a joint. This behavior has been seen right before they attacks their prey.

• Key Behaviors
• natatorial natatorial
• nocturnal nocturnal
• motile motile
• migratory migratory
• solitary solitary

Home Range

The home range for pharaoh cuttlefish is about 10 to 40 m, and 40 to 80 m during mating season. Their range is vastly affected by the geographic region and can go as deep as about 130 m.

Communication and Perception

Pharaoh cuttlefish communicate primarily using visual cues such as their unique ability to change the color and texture of their skin. While their color is generally a molted pattern, they can change it to a zebra-striped pattern to convey aggression. This zebra striping can also be used to represent gender during mating season. This unique ability is also paired with other visual cues like their swimming posture and the position of their tentacles.

Since pharaoh cuttlefish are fairly solitary creatures, most of their intraspecific communication is conducted during mating season. Their interspecific communication is limited to escaping predators using ink or camouflage, and when changing their color and body position to approach their prey.

• Communication Channels
• visual visual

• Other Communication Modes
• mimicry mimicry

• Perception Channels
• visual visual
• tactile tactile

Food Habits

Pharaoh cuttlefish eat mysids (order Mysida ) of all sizes as well as brine shrimp ( Artemia ), crabs, molluscs, fish, and sometimes even other cuttlefish. Like other cuttlefish, they are ambush predators. This means that they are extremely adept at camouflaging themselves. They hide themselves by changing their texture and color to blend in with their surroundings and hide from unsuspecting prey. They go about attacking their prey in two ways: they either open their eight arms and shoot out their two tentacles to quickly capture their prey, or they pounce on their prey using their arms to hold them in place. In both of these cases, pharaoh cuttlefish use their beaks and radulae to tear into their prey. Adults and hatchlings hunt at night, and hatchlings begin to hunt when they reach mantle lengths of about 8 mm. However, they can recognize prey as soon as they hatch.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • eats non-insect arthropods
  • molluscivore molluscivore

• Animal Foods
• fish
• mollusks
• aquatic crustaceans

Predation

Predators of pharaoh cuttlefish include sharks, dolphins, seals, seabirds, whales, and even other cuttlefish. In order to escape their predators, pharaoh cuttlefish use jet propulsion and ink ejection to make a quick exit while simultaneously disorientating potential predators. They also avoid predation by changing their coloration and texture to better match their surroundings, which helps them avoid being spotted.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Pharaoh cuttlefish expend large amounts of energy mating and escaping predators. These actions expend a lot of metabolic energy, and thus require a large amount of energy, acquired through hunting. Pharaoh cuttlefish have a large range of prey they feed upon and a large dispersion pattern. This makes them crucial consumers that fill various ecological niches.

Economic Importance for Humans: Positive

Pharaoh cuttlefish are commonly bred and fished for consumption and research. Their ink has been used for various homeopathic medicinal practices, such as cures for menstrual cramps and even depression. People have also been known to keep pharaoh cuttlefish as pets. Though the most common use for pharaoh cuttlefish is the extraction of their cuttlebone for pet birds to easily gain calcium.

• Positive Impacts
• pet trade pet trade
• food food
• body parts are source of valuable material
• source of medicine or drug source of medicine or drug

Economic Importance for Humans: Negative

Pharaoh cuttlefish have no known adverse effects on human populations.

Conservation Status

Pharaoh cuttlefish are considered data deficient by the IUCN, but they do face threats to their populations. The increase of ocean acidification due to increased carbon dioxide levels within the atmosphere is a major threat not only to pharaoh cuttlefish, but also other marine organisms. The increased levels of CO2 has also been shown to increase cuttlebone density, which negatively affects their buoyancy control. They are also commonly fished and may be subjected to overfishing, thus depleting their populations. Current conservation efforts include fishing quotas in Yemen, and reducing carbon emissions around the world.

Other Comments

Pharaoh cuttlefish are one of two cuttlefish species that have been found to completely regenerate limbs after amputation. It takes about 39 days for their appendages to completely regenerate, including new chromatophores, suction cups, normal shape, and complete use for social communication and predation. The regeneration process is consistent and statistically predictable throughout the whole species.

Additional Links

Encyclopedia of Life

Contributors

Sydney Wayne (author), Colorado State University, Kate Gloeckner (editor), Colorado State University, Galen Burrell (editor), Special Projects.

References

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