Kary Mar
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The sea squirt Didemnum ligulum is a great example to think about the distribution of species.
The sea squirt comes from the Western Central Pacific and was photographed by naturalist Dr. Karine Marangon in the Western Indian Ocean.
With most ascidians, it is not possible to identify the species with certainty from a photograph; only microscopic examination is crucial.
This sea squirt however has an almost unmistakable ID feature, it has a white colored exhalation opening at the tip with white toothlike serrated structures/markings.
So how can the sessile sea squirt (mobile only in larval stage) be able to realize its way from the Pacific to the Western Indian Ocean (or maybe even vice versa)?
Unfortunately, we must remain guilty of the actual answer, but we have once summarized a whole series of basic possibilities of dispersal:
Dispersal of species:
- Drifting by strong wave action, storms.
- Active dispersal by swimming or crawling (e.g. fish and crustaceans)
- Filling and emptying of ships' ballast water tanks at various locations
- Attachment to ship hulls and detachment in other areas
- Species dispersal through attachment of fertilized eggs in the plumage of seabirds
- deliberate introduction of species by humans for breeding reasons
- escape of specimens from breeding facilities
- transport of animals on floating objects (e.g. on uprooted trees)
- deliberate release of species (see scorpion fish in the Caribbean)
- accidental release of animals at central collection and shipping sites (cardinalfish Pterapogon kauderni in Lembeh Strait)
- escape of individuals in transport accidents
If anyone knows of any other means of dispersal, we would greatly appreciate being notified.
Didemnum ligulum forms colonial ascidians that cover the substrate 15 to 20 cm and consist of cushion-shaped structures that have a white-colored exhalation opening with white teeth at the tip.
They are often pinkish purple, but can be many different colors, including yellow, orange, red, or brown.
The inhalation openings are evenly distributed on the tunica and are also finely serrated.
Sea squirts feed by inhaling water through the oral siphon, which then passes through the gills into the peribranchial cavity. The water and nutrients are absorbed with the help of the mucus lining the inner wall before exiting through the cloacal siphon.
Food is filtered and passed into the stomach, and waste is excreted through the anus, which is located in the cloacal siphon. The tunica is made of tunicin, a substance similar to cellulose in plants, which is unique in the animal kingdom.
Ascidians are hermaphrodites; fertilization occurs in water and results in a tadpole-shaped larva 2-3 mm long.
The tail has a dorsal tendon, a primitive backbone called a notochord, which allows them to swim freely and disappears in the adult stage, as does most of their nervous system.
At this stage they attach themselves to rocks or other objects and form colonies.
Although they look like simple organisms, their life cycle is quite complex.
Rock or coral bottoms
Colonies of Didemnum ligulum encrust all types of substrates, whether vegetable, animal, gravelly, The sea squirt Didemnum ligulum is a great example to think about the distribution of species.
The sea squirt comes from the Western Central Pacific and was photographed by naturalist Dr. Karine Marangon in the Western Indian Ocean.
With most ascidians, it is not possible to identify the species with certainty from a photograph; only microscopic examination is crucial.
This sea squirt however has an almost unmistakable ID feature, it has a white colored exhalation opening at the tip with white toothlike serrated structures/markings.
So how can the sessile sea squirt (mobile only in larval stage) be able to realize its way from the Pacific to the Western Indian Ocean (or maybe even vice versa)?
Unfortunately, we must remain guilty of the actual answer, but we have once summarized a whole series of basic possibilities of dispersal:
Dispersal of species:
- Drifting by strong wave action, storms.
- Active dispersal by swimming or crawling (e.g. fish and crustaceans)
- Filling and emptying of ships' ballast water tanks at various locations
- Attachment to ship hulls and detachment in other areas
- Species dispersal through attachment of fertilized eggs in the plumage of seabirds
- deliberate introduction of species by humans for breeding reasons
- escape of specimens from breeding facilities
- transport of animals on floating objects (e.g. on uprooted trees)
- deliberate release of species (see scorpion fish in the Caribbean)
- accidental release of animals at central collection and shipping sites (cardinalfish Pterapogon kauderni in Lembeh Strait)
- escape of individuals in transport accidents
If anyone knows of any other means of dispersal, we would greatly appreciate being notified.
Didemnum ligulum forms colonial ascidians that cover the substrate 15 to 20 cm and consist of cushion-shaped structures that have a white-colored exhalation opening with white teeth at the tip.
They are often pinkish purple, but can be many different colors, including yellow, orange, red, or brown.
The inhalation openings are evenly distributed on the tunica and are also finely serrated.
Sea squirts feed by inhaling water through the oral siphon, which then passes through the gills into the peribranchial cavity. The water and nutrients are absorbed with the help of the mucus lining the inner wall before exiting through the cloacal siphon.
Food is filtered and passed into the stomach, and waste is excreted through the anus, which is located in the cloacal siphon. The tunica is made of tunicin, a substance similar to cellulose in plants, which is unique in the animal kingdom.
Ascidians are hermaphrodites; fertilization occurs in water and results in a tadpole-shaped larva 2-3 mm long.
The tail has a dorsal tendon, a primitive backbone called a notochord, which allows them to swim freely and disappears in the adult stage, as does most of their nervous system.
At this stage they attach themselves to rocks or other objects and form colonies.
Although they look like simple organisms, their life cycle is quite complex.
Colonies of Didemnum ligulum encrust all types of substrates, whether vegetable, animal, or gravelly, rock or coral bottoms
The sea squirt comes from the Western Central Pacific and was photographed by naturalist Dr. Karine Marangon in the Western Indian Ocean.
With most ascidians, it is not possible to identify the species with certainty from a photograph; only microscopic examination is crucial.
This sea squirt however has an almost unmistakable ID feature, it has a white colored exhalation opening at the tip with white toothlike serrated structures/markings.
So how can the sessile sea squirt (mobile only in larval stage) be able to realize its way from the Pacific to the Western Indian Ocean (or maybe even vice versa)?
Unfortunately, we must remain guilty of the actual answer, but we have once summarized a whole series of basic possibilities of dispersal:
Dispersal of species:
- Drifting by strong wave action, storms.
- Active dispersal by swimming or crawling (e.g. fish and crustaceans)
- Filling and emptying of ships' ballast water tanks at various locations
- Attachment to ship hulls and detachment in other areas
- Species dispersal through attachment of fertilized eggs in the plumage of seabirds
- deliberate introduction of species by humans for breeding reasons
- escape of specimens from breeding facilities
- transport of animals on floating objects (e.g. on uprooted trees)
- deliberate release of species (see scorpion fish in the Caribbean)
- accidental release of animals at central collection and shipping sites (cardinalfish Pterapogon kauderni in Lembeh Strait)
- escape of individuals in transport accidents
If anyone knows of any other means of dispersal, we would greatly appreciate being notified.
Didemnum ligulum forms colonial ascidians that cover the substrate 15 to 20 cm and consist of cushion-shaped structures that have a white-colored exhalation opening with white teeth at the tip.
They are often pinkish purple, but can be many different colors, including yellow, orange, red, or brown.
The inhalation openings are evenly distributed on the tunica and are also finely serrated.
Sea squirts feed by inhaling water through the oral siphon, which then passes through the gills into the peribranchial cavity. The water and nutrients are absorbed with the help of the mucus lining the inner wall before exiting through the cloacal siphon.
Food is filtered and passed into the stomach, and waste is excreted through the anus, which is located in the cloacal siphon. The tunica is made of tunicin, a substance similar to cellulose in plants, which is unique in the animal kingdom.
Ascidians are hermaphrodites; fertilization occurs in water and results in a tadpole-shaped larva 2-3 mm long.
The tail has a dorsal tendon, a primitive backbone called a notochord, which allows them to swim freely and disappears in the adult stage, as does most of their nervous system.
At this stage they attach themselves to rocks or other objects and form colonies.
Although they look like simple organisms, their life cycle is quite complex.
Rock or coral bottoms
Colonies of Didemnum ligulum encrust all types of substrates, whether vegetable, animal, gravelly, The sea squirt Didemnum ligulum is a great example to think about the distribution of species.
The sea squirt comes from the Western Central Pacific and was photographed by naturalist Dr. Karine Marangon in the Western Indian Ocean.
With most ascidians, it is not possible to identify the species with certainty from a photograph; only microscopic examination is crucial.
This sea squirt however has an almost unmistakable ID feature, it has a white colored exhalation opening at the tip with white toothlike serrated structures/markings.
So how can the sessile sea squirt (mobile only in larval stage) be able to realize its way from the Pacific to the Western Indian Ocean (or maybe even vice versa)?
Unfortunately, we must remain guilty of the actual answer, but we have once summarized a whole series of basic possibilities of dispersal:
Dispersal of species:
- Drifting by strong wave action, storms.
- Active dispersal by swimming or crawling (e.g. fish and crustaceans)
- Filling and emptying of ships' ballast water tanks at various locations
- Attachment to ship hulls and detachment in other areas
- Species dispersal through attachment of fertilized eggs in the plumage of seabirds
- deliberate introduction of species by humans for breeding reasons
- escape of specimens from breeding facilities
- transport of animals on floating objects (e.g. on uprooted trees)
- deliberate release of species (see scorpion fish in the Caribbean)
- accidental release of animals at central collection and shipping sites (cardinalfish Pterapogon kauderni in Lembeh Strait)
- escape of individuals in transport accidents
If anyone knows of any other means of dispersal, we would greatly appreciate being notified.
Didemnum ligulum forms colonial ascidians that cover the substrate 15 to 20 cm and consist of cushion-shaped structures that have a white-colored exhalation opening with white teeth at the tip.
They are often pinkish purple, but can be many different colors, including yellow, orange, red, or brown.
The inhalation openings are evenly distributed on the tunica and are also finely serrated.
Sea squirts feed by inhaling water through the oral siphon, which then passes through the gills into the peribranchial cavity. The water and nutrients are absorbed with the help of the mucus lining the inner wall before exiting through the cloacal siphon.
Food is filtered and passed into the stomach, and waste is excreted through the anus, which is located in the cloacal siphon. The tunica is made of tunicin, a substance similar to cellulose in plants, which is unique in the animal kingdom.
Ascidians are hermaphrodites; fertilization occurs in water and results in a tadpole-shaped larva 2-3 mm long.
The tail has a dorsal tendon, a primitive backbone called a notochord, which allows them to swim freely and disappears in the adult stage, as does most of their nervous system.
At this stage they attach themselves to rocks or other objects and form colonies.
Although they look like simple organisms, their life cycle is quite complex.
Colonies of Didemnum ligulum encrust all types of substrates, whether vegetable, animal, or gravelly, rock or coral bottoms
