The lagoon jellyfish is found in the ocean, where it tends to dwell within the top 2.5 m of the water during the day to allow its symbiotic zooxanthellae access to light. Sunlight governs its life, especially in the Palau lakes, and this species follows the sun from west to east until it reaches the shadows near the shore. When the sun is setting, the lagoon jellyfish sinks to lower levels of its habitat. (Dawson, 2005; Graham, et al., 2001; Hale, 1999; Mayer, 1910; Sugiura, 1963; Sugiura, 1964)requires specific temperature, salinity, and exogenous cues for proper strobilation (transverse fission). They also respond evolutionarily to their specific habitats, as demonstrated by the endemic speciation of in the Palau lakes.
The lagoon jellyfish has many subspecies that grow more dissimilar as they age. There are considerable morphological differences among subspecies that live in different environments, gather in different populations, and even between the individual jellyfish themselves. Four main morphological differences are used to differentiate between these subspecies: the number and shape of the velar lappets (flaps), the length of the mouth arms relative to bell radius, the length of the terminal clubs relative to bell radius, and color. The following summarizes the features that are considered characteristic of the traditional lagoon jellyfish. (Dawson, 2005; Mayer, 1910; Sasaki, et al., 2002)
Full-fledged medusas are dioecious and can be identified by sampling a part of their reproductive tissue and observing it under a dissecting microscope. Females also have characteristic brood filaments on their oral arms and disk. Medusa males release sperm that swim to eggs either within the brood filaments of the female or inside of her. A sexual generation (medusa) alternates with an asexual generation (polyp). There are no data on mate selection. (Calder, 1982; Kramp, 1961; Raskoff, et al., 2003; Sugiura, 1963; Uchida, 1926)
Asexual reproduction by budding can occur year round, though strobilation can only occur with cooler water temperatures since water that is too warm causes the symbiotic zooxanthallae to fail. Loss of the zooxanthellae would eliminate seventy percent of the lagoon jellyfish's food source. Other than this, the only specific observation made on how (Calder, 1982; Graham, et al., 2001; Hofmann and Crow, 2002; Raskoff, et al., 2003; Sugiura, 1964)breeds in the wild is that ephyrae do not seem to emerge unless the sea water temperature is around 22 degrees C. polyps can reproduce asexually year-round by budding off, while medusa formation via strobilation requires lower temperatures because high temperatures kill the zooxanthellae needed for medusae to survive.
These jellyfish have a nerve net along the bell as well as marginal sensory organs that determine the contractions which propel the medusa. All Scyphozoa have receptors that detect a variety of stimuli, including light (ocelli), smell, and touch (sensory lappets) as well as a statocyst, which coordinates balance. These are found in the triangular clubs (rhopalia), which in turn also allow control of stimulation of the statocyst so that the jellyfish can adjust the direction it is swimming. (Hale, 1999; Nicol, 1960)
Yachun Chang (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, Renee Mulcrone (editor), Special Projects.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
reproduction that is not sexual; that is, reproduction that does not include recombining the genotypes of two parents
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
fertilization takes place outside the female's body
union of egg and spermatozoan
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
fertilization takes place within the female's body
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
generally wanders from place to place, usually within a well-defined range.
found in the oriental region of the world. In other words, India and southeast Asia.
reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
an animal that mainly eats plankton
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.
a form of body symmetry in which the parts of an animal are arranged concentrically around a central oral/aboral axis and more than one imaginary plane through this axis results in halves that are mirror-images of each other. Examples are cnidarians (Phylum Cnidaria, jellyfish, anemones, and corals).
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
remains in the same area
non-motile; permanently attached at the base.
Attached to substratum and moving little or not at all. Synapomorphy of the Anthozoa
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).
uses sight to communicate
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
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