Parasitism, Coral Reefs, Oligochaeta, and Biological Concepts

Adaptation to Parasitism

Normally, endoparasites are animals that have undergone major structural changes regarding their architectural pattern, such as the disappearance of unnecessary structures. Locking mechanisms are another common characteristic in parasitic animals. Reproduction and life cycle are significantly affected in animal parasites. Populations often maintain very low levels, so finding a partner can be a problem. The appearance of hermaphroditism ensures reproduction despite the cost of producing two reproductive systems. The production of a high number of eggs compensates for the low probability of one completing the life cycle. The cyst is one of the more developed structures in these animals. Finally, to complete the life cycle, an infective stage is usually required, which enters the host and crosses its defensive barriers to reach its final location. The coevolution of parasites and hosts is driven by natural selection.

Coral Reefs

Large calcium carbonate formations that appear in warm, shallow tropical seas, deposited by living organisms over thousands of years. They are among the most productive ecosystems and maintain a great diversity of life forms. The most important organisms that precipitate CaCO3 are hermatypic corals (reef builders) and coralline algae. The required environmental conditions are: moderate heat, lots of light, salinity, and undiluted seawater. This limits coral reefs to shallow water. Coral reefs are being harmed, mostly by human factors, such as nutrient enrichment due to agricultural fertilizers (eutrophication) and the overfishing of herbivorous fish, which contributes to excessive algae growth. Global warming also has a negative impact.

Types of Coral Reefs

• Fringing
• Barrier
• Atoll

Parts of a Coral Reef

• Reef front or anterior slope
• Reef crest
• Reef plain

Oligochaeta Benefits

Oligochaeta provide benefits such as food, digging tunnels, and excreting. They also stimulate plant growth and affect soil structure by:

• Increasing water infiltration
• Preventing erosion
• Increasing overall porosity
• Developing surface roughness

They also have effects on soil organic matter and nutrient dynamics by preventing the rapid loss of nutrients and soil organic matter.

Types of Oligochaeta

Epigeic Species

These species do not create galleries and live in the topsoil. Their effects are limited primarily to the top layer of mulch. They are transformers that change the physical-chemical properties of the soil and reduce the proportion of carbon and nitrogen. The manure produced by these worms is rich in organic matter, which implies a greater availability of nutrients for plant roots.

Anacics

These worms live in galleries, which improve water penetration. Oxygen and other gases, along with mucus and organic matter-rich protein trails, are beneficial for root growth in deep layers.

Endogeal

These worms have developed complex interrelationships with soil microorganisms to obtain nutrients from poor-quality food. Some are able to digest organic matter using enzymes.

Trichoid Sensilla

Trichoid sensilla are sensory organs of arthropods that are activated by mechanoreception, i.e., mechanical stimuli (touch, pressure, or vibration). These sensilla are in contact with a cell or nerve ending.

Biological Species Concept

A species is a reproductive community of populations (isolated from others in reproduction) that occupies a specific niche in nature. It is identified according to reproductive properties and not by specific characters. The study of the population range in terms of morphology, chromosome structure, and molecular genetic traits will help to identify geographic boundaries of communities.

Evolutionary Species Concept

A single lineage of ancestor-descendant populations that maintains its identity from other lineages and has its own evolutionary tendencies and historical fate.

Typological Species Concept

Species are considered independent and immutable entities that have a defined pattern or archetype. Scientists recognize species through the designation of a type specimen, labeled and placed in a museum.