SEA SLUGS
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Context: A citizen science project documents unique sea slugs from Visakhapatnam coast.
Details:
What are slugs?
- Sea slugs belong to Phylum Mollusca and Class Gastropoda.
- They look like naked snails, i.e., without shells.
- Sea slugs are of course those found in the sea. There are also slugs that live on land.
Types:
- Sea slugs may be generally differentiated into two main groups.
- Members of one group breathe with lungs. These include pulmonate sea slugs such as the Onch slugs of the Family Onchidiidae.
- Members of another group breathe with gills. These include the Opisthobranchs or just plain sea slugs.
Where seen?
- Onch slugs can be found among the rocks near the high water mark, while other slugs are found further down where it is almost always covered in water.
- Some are burrowing and many are found on or near their food.
- Some sea slugs are stunningly beautiful, among them, nudibranchs.
Features:
- Sea slugs range from large sea hares of 10cm to tiny nudibranchs 1cm or less.
- Sea slugs generally lack large external shells.
- Some many have external shells but cannot fully retract their bodies into these shells like other 'regular' snails do. Other sea slugs may have internal shells.
- Most sea slugs don't have any shells at all.
- Although they lack shells, slugs are not helpless. Some taste bad, others release toxic or irritating substances.
- Yet others incorporate stingers of sea anemones, hydroids and other cnidarians that they feed on and use these to protect themselves.
What do they eat?
- As a group, sea slugs eat a wide variety of plants and animals.
- But each species usually specialises in one kind of food.
Threats:
- Some slugs may release highly toxic substances when stressed.
- Like other creatures of the intertidal zone, they are affected by human activities such as reclamation and pollution.
- Trampling by careless visitors and over-collection can also have an impact on local populations.
PRACTICE QUESTION Q) Which of the following statements is/are correct with reference to Sea Slug? a. They lack an external shell. b. They are found in sea only.
Answer: Option 2 |