To answer the question "In aquatic environment the types of benthic animals are determined by," we will follow these steps:
### Step-by-Step Solution:
1. **Define Benthic Animals**:
- Benthic animals, also known as benthos, are organisms that live at the lowest level of a water body, including the sediment surface and some sub-surface layers. Examples include sea anemones, sponges, corals, and crabs.
2. **Identify Factors Influencing Benthic Animals**:
- The types of benthic animals in an aquatic environment are influenced by several factors, including:
- Type of water (freshwater vs. saltwater)
- Sediment characteristics
- Light availability
- Nutrient availability
3. **Focus on Sediment Characteristics**:
- Among these factors, sediment characteristics play a crucial role. This includes the type of sediment (sand, mud, gravel), the amount of organic matter present, and the physical structure of the sediment.
- Benthic animals may live above the seabed, inside the seabed, or attached to the bottom, depending on the sediment type.
4. **Consider Light and Nutrient Availability**:
- Light availability is limited in deeper water, affecting photosynthetic organisms and indirectly influencing the benthic community.
- Nutrient availability is also important as it affects the growth of primary producers, which in turn supports the benthic food web.
5. **Conclusion**:
- While all the factors mentioned can influence benthic animals, the most direct determinant of the types of benthic animals is the sediment characteristics. Therefore, the correct answer to the question is that the types of benthic animals are determined by the type of sediment characteristics.
### Final Answer:
The types of benthic animals in an aquatic environment are determined by the type of sediment characteristics.
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