''Julia exquisita'' is a small species of
sea snail
Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...
with a green
bivalve
Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...
shell. It is a marine gastropod
mollusk in the family
Juliidae.
This species can be found in shallow tropical habitats throughout the Pacific, and are known for their feeding of
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
, in which
photosynthetic
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...
cells are taken up and incorporated into the snails' body tissues for energy storage.
Distribution
''Julia exquisita'' is a
benthic
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...
organism, often residing in
intertidal flats.
Individuals typically live at depths of about 3 meters, but have been observed at depths as low as 10 meters.
''Julia exquisita'' prefers a warmer climate with available sunlight, meaning that their distribution is relegated to tropical Pacific waters. The species has the greatest observed abundance in the
coral triangle, along the coasts of Hawaii, and in the Caribbean,
but have also been found along the coast of Madagascar, Australia, and other Indo-West Pacific islands.
Description
Individuals of ''Julia exquisita'' are dark green in color with a long thin body and a characteristic bivalve shell. They range from 4mm-6mm in length, with a dorsal foot roughly as wide as their neck.
The anterior edge of the grooved foot extends to a round oral
tentacle used for feeding. Many individuals exhibit small white patches on their body which are often surrounded by brown rings.
White eye prominences lead to thin, squared
rhinophores extending from the head which act as scent and taste receptors. Within the oral feeding tentacle is a
radula
The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...
, or sharp tooth, which is used to feed by scraping their food source.
The
shell is the best defining characteristic of this species, as it is a two-parted convex dorsal shell which greatly resembles that of bivalves.
The shell is bright green in color, typically with red-brown or white bands surrounding its concentric lines. Shells have a round anterior margin and are ovular in shape.
The internal anatomy of ''Julia exquisita'' is similar to that of other bivalve gastropods, with 2 shell valves surrounding a visceral mass containing their vital organs. Key anatomical differences between ''Julia exquisita'' and other similar species include proportionally larger
adductor muscles
The adductor muscles of the hip are a group of muscles mostly used for bringing the thighs together (called adduction).
Structure
The adductor group is made up of:
*Adductor brevis
*Adductor longus
*Adductor magnus
* Adductor minimus This is o ...
, which are used to shut the two shell valves, as well as a slightly more complex penis.
Reproduction and Development
Adult members of the species reproduce using internal fertilization in which male sperm fertilize female eggs which are laid and left to develop into
larvae
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
. While in
ovum
The egg cell, or ovum (plural ova), is the female reproductive cell, or gamete, in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one). The term is used when the female gamete is ...
development, ''Julia Exquisita'' experiences a
trochophore stage before assuming their final larval form.
Larvae take on a planktonic form after hatching,
and eventually use mucous threads to settle on algae covered surfaces. Once settled, larvae undergo
metamorphosis
Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...
until they reach their adult life stage.
Their characteristic bivalve shell is fully produced in about three days.
Feeding and Behavior
''Julia exquisita'' are opportunistic grazers.
Like other similar species, individuals use their sharp radula to pierce the cells of algae and suck out the cellular contents. These contents are then digested using mucous within the digestive tract.
Their feeding habits also influence their behavior, as individuals typically tether themselves to algal colonies using mucous-like threads extending from their dorsal foot. Individuals can withdraw into their shell while still being tethered, allowing them to protect themselves from predation while staying attached to their food source.
Like other members of the Juliidae family, ''Julia exquisita'' performs
kleptoplasty in which functional contents of the algal cells are incorporated into their bodies. Specifically,
chloroplasts from the algae are kept photosynthetically functional within the digestive gland.
This allows ''Julia exquisita'' to continue to use the energy produced through algal photosynthesis, while also contributing to the green color characteristic of this species.
References
External links
* Kay E. (1962) "''Julia exquisita'' Gould, a bivalved gastropod". ''
Pacific Science'' 16(4): 434-435
PDFphotos
{{DEFAULTSORT:Julia Exquisita
Juliidae
Gastropods described in 1862