What is Abalone?
Abalones are marine snails from the Haliotidae family, with one genus, Haliotis. They stand out for their ear-shaped shells and colorful, shiny insides. Feeding mainly on seaweed, they live in various ocean settings, often in cool, kelp-rich areas. Also called ear shells, sea ears, and muttonfish, these sea creatures inhabit cold coastal waters worldwide, from New Zealand to the west coast of North America. Abalones have a unique, low spiral shell with several breathing holes and a shiny inside known as nacre. This feature makes them highly sought-after for jewelry and decorative items, as well as a gourmet treat. Their delicious meat is enjoyed in different ways worldwide, including raw, cooked, and in delicacies such as sushi. However, due to overfishing and disease, some abalone species face extinction risks. This has led to strict rules and a move towards sustainable farming practices, especially in places like southern Australia where they are commercially vital.
Habitat and Distribution
Abalone thrive in places like intertidal zones and up to depths of around 60 feet. These sea snails prefer rocky substrates and reefs, especially in spots with high wave exposure and crevices where their main food source, drift algae, gathers. Different types of abalone are located in specific regions. For example, the black abalone lives along the coast from Point Arena, California, down to Bahia Tortugas and Isla Guadalupe, Mexico. On the other hand, the green abalone’s habitat extends from Point Conception, California, to Bahia de Magdalena, Mexico. In Western Australia, abalone species like Roe’s abalone can be found from Shark Bay to Victoria, dwelling in shallow limestone reefs. The wide distribution of abalone shows their ability to adapt to various marine environments. However, their populations tend to concentrate in particular areas due to factors like food availability, habitat conditions, and environmental threats.
Types of abalone
1. Haliotis tuberculata Linnaeus
The European abalone, Haliotis tuberculata, is an important species for aquaculture due to its commercial value. Research comparing wild and hatchery populations from the Channel Islands found that while hatchery stocks maintain similar genetic diversity levels as the wild populations, rare alleles are reduced in third-generation hatchery stock. However, there is no sign of inbreeding or decreased heterozygosity, indicating that current hatchery practices effectively preserve genetic diversity for this species.
2. Haliotis rufescens (Red Abalone)
The red abalone, also known as Haliotis rufescens, has had its genetic code analyzed to help with conservation and aquaculture work. Researchers have looked at the genes of this species and other abalones found in the Eastern Pacific like the green, pink, pinto, black, and white abalone to understand their genetic differences and family tree. The white abalone, which is at risk of disappearing, has the least genetic variation among them, showing why it’s important to have strategies based on their genes to protect them.
3. Haliotis fulgens (Green Abalone) and Haliotis discus (Japanese Abalone)
In a mixed farming system, the green abalone, Haliotis fulgens, and the Japanese abalone, Haliotis discus, were observed along with the red abalone. These species were given sea lettuce to eat, and their growth and feeding efficiencies were measured. The green abalone displayed the highest growth efficiency, likely due to the experiment’s temperature conditions, indicating that specific environmental factors play a crucial role in successful aquaculture.
4. Southern Australian Abalones
Southern Australia is home to five types of abalone, with three being quite important for commercial purposes: Haliotis laevigata, Haliotis roei, and Haliotis ruber. These abalone have their own favorite spots to hang out and eat, enjoying different kinds of algae and sea grasses. Scientists have looked closely at how these abalone interact with each other and with predators, and where they like to live, all to figure out how they manage to live together without fighting too much.
5. Haliotis asinina Linné (Tropical Abalone)
The tropical abalone, Haliotis asinina, is well-known for being highly active and feeding at night on coral reefs. It has a remarkable ability for aerobic metabolism, which helps it sustain its long and fast exercise habits. Unlike temperate abalones, H. asinina doesn’t rely on increased anaerobic metabolism. Instead, it can lower both its aerobic and anaerobic metabolism when there’s not enough oxygen in its environment.
6. Haliotis discus hannai Ino (Pacific Abalone)
A new color variation has been discovered in the Pacific abalone, known as Haliotis discus hannai. This variant showcases an orange hue instead of the usual green shell color. Studies on genetics indicate that the color of the shell is mainly controlled by genetics, but diet can also play a role in determining the color. This discovery is essential for unraveling the genetic factors behind shell color and understanding its potential importance for adaptation in abalones.
7. Haliotis discus discus (Disk Abalone) and Turbo cornutus (Spiny Top Shell)
The disk abalone, known as Haliotis discus discus, and the spiny top shell, which is Turbo cornutus, are important gastropods. Scientists have studied their immune systems by looking at their hemocytes. They found that these two creatures have different types of hemocytes and perform different immune functions. The disk abalone has shown higher phagocytic activity, which is its ability to engulf and digest foreign particles. These discoveries help us understand how these creatures respond to challenges from their environment and diseases.
8. General Abalone Species
Abalones have a long history as a sought-after delicacy, especially in Asian cultures. These marine gastropods are prized for their distinct texture, flavor, and nutritional benefits. Proper processing techniques such as canning and drying play a crucial role in preserving the high quality of abalones. Exploring the potential of abalones as a nutritious food source holds promise for future research endeavors.
9. Chinese Medicinal Abalone Shells
In traditional Chinese medicine, abalone shells are utilized for their healing properties. A recent survey has pinpointed nine kinds of abalone shells available in the market, including three varieties not found in the Chinese Pharmacopeia. The most prevalent shells come from Haliotis ruber and H. discus hannai, showcasing the assortment of abalone species used in traditional methods.
10. Pacific Abalones (Haliotidae)
Researchers studied six types of Pacific abalones along the Korean coasts by analyzing their mitochondrial DNA sequences. Through this study, they were able to group the species into two distinct categories. One group includes Haliotis discus hannai, H. discus discus, H. madaka, and H. gigantea, while the other consists of H. diversicolor supertexta and H. diversicolor diversicolor. These genetic findings are essential for identifying the species accurately and understanding their evolutionary relationships.
Nutritional value of abalone
Abalone is well-known for its rich nutritional content, especially as a protein source. The meat of Japanese abalone (Haliotis discus hannai Ino) is packed with protein, carbs, fats, and ash, with protein being the highest at 15.87 g/100 g. Not only is this protein abundant, but it’s also super easy for the body to digest, with estimates showing around 92% digestibility for certain parts. Abalone is also full of essential amino acids like arginine and lysine, which are crucial for our health. When it comes to minerals, potassium takes the lead in abalone. Additionally, abalone is a great source of polyunsaturated fatty acids (PUFAs) that are necessary for keeping our cell membranes healthy and working well. What abalone eats influences its nutritional value, with seaweed playing a key role in its natural diet and contributing to its amino acids and fats. Overall, abalone is a nutritious choice from the sea, offering top-notch protein, essential amino acids, minerals, and beneficial fats.
Health benefits of Abalone
Abalone has long been eaten for its believed health perks and is now known for its natural compounds that could be used for treatments. These compounds, like sugars, proteins, and fats, help make it good for your health.
1. Oxidative stress management
Abalone can benefit from dietary supplements that boost their antioxidant capacity and resistance to oxidative stress. Research shows that adding chromium yeast (CrYst) and astaxanthin (ASTA) to their diet can significantly enhance abalone’s growth and antioxidative abilities, while also improving their ability to withstand heat stress, which often leads to oxidative stress. Studies on abalone have highlighted the essential role of antioxidant enzymes in fighting oxidative stress and regulating immune responses during pathogen exposure. Moreover, supplementing abalone sperm cryopreservation with saccharides has been found to strengthen antioxidant defenses and reduce oxidative stress-induced cell death. These discoveries indicate that specific dietary components can strengthen abalone’s antioxidant systems, promoting better health and resilience against environmental stressors.
2. Alleviate inflammation
Studies show that different parts of abalone, like the meat, guts, and even leftovers like the intestines, have special compounds that can really help reduce inflammation. These compounds work in various ways, like stopping the body from making inflammatory substances such as IL-1β, TNF-α, and IL-6, and calming down certain pathways in immune cells. Moreover, abalone extracts seem to ease inflammation in other situations, like sunburn and gut issues in mice, hinting that they could be used to treat a wide range of problems. The antioxidants in abalone also play a part in fighting inflammation by battling harmful molecules and shielding against stress from oxidation, which often triggers inflammation. These discoveries back up the traditional use of abalone as a superfood and show potential for using it as a health supplement or medicine to relieve inflammation.
3. Inhibit cancer development
Abalone meat contains bioactive compounds that may help fight cancer. Scientists have found different molecules in abalone that can slow down tumor growth. For example, a new peptide from Haliotis discus hannai can block the spread of tumor cells and could be a key ingredient in future cancer treatments. It works by targeting specific pathways in the body and interfering with the growth of tumors. Some polysaccharides from Pleurotus abalonus, a type of mushroom related to abalone, have shown promise in stopping the growth of breast cancer cells. These substances seem to play a role in preventing cancer by affecting how cells multiply. Abalone extracts have also been shown to slow down tumor growth and boost the immune system’s ability to fight cancer. They help immune cells work better against tumors, suggesting they could be used in cancer treatment. Abalone extract from the insides of the sea snail has been found to slow down tumors by changing certain levels in the body and helping immune cells attack cancer cells. These discoveries indicate that substances from abalone could be beneficial in cancer treatment by targeting different stages of tumor growth.
4. Maintain a healthy heart
Research indicates that abalone contains active compounds that can reduce inflammation and oxidative stress, promoting heart health. Some specific peptides from abalone have been shown to block enzymes that are linked to heart diseases, suggesting they could be used for treatment and prevention. Moreover, abalone guts fermented with Lactobacillus casei 001 can lower blood pressure by inhibiting an enzyme that helps regulate it. These discoveries imply that abalone and its byproducts might be valuable as functional foods or supplements for heart health and preventing heart diseases.
5. Support gastrointestinal Health
The compounds found in abalone guts can ease inflammation and fight off harmful molecules in the body. A substance from abalone guts can stop the release of histamine and reduce inflammation in human cells, hinting at its potential to treat inflammatory conditions. Another study showed that abalone gut extracts have antioxidants that can calm down inflammation in certain cells by interfering with a specific signaling pathway. These discoveries suggest that abalone gut compounds might help keep our gut healthy by regulating the body’s immune response and shielding it from damage caused by oxidative stress. This makes them a promising option for improving gut health as a supplement or treatment.
6. Assists Joint and Bone Health
Substances in abalone like polysaccharides, proteins, and fatty acids have been proven to fight inflammation and act as antioxidants, which are crucial for keeping joints healthy. Research also suggests that materials made from abalone shells can help regenerate bones, showing promise for fixing bone defects. Peptides from abalone have been found to stop enzymes called matrix metalloproteinases, which break down bone and cartilage, potentially protecting against joint diseases. Moreover, abalone intestine extracts can boost the formation of bone cells and mineralization, vital processes for maintaining bone strength. These discoveries point to the potential of abalone as a supplement for improving joint and bone health.
Sustainability of Abalone
Abalone is known for its abundance of beneficial compounds that enhance its healing properties, making it a valuable functional food and a source of health supplements. These compounds, such as complex carbohydrates, proteins, and healthy fats, have been found to possess properties like fighting off harmful substances, preventing blood clots, reducing inflammation, battling microbes, and even inhibiting cancer growth. Researchers are also looking into ways to support the sustainability of abalone farming by studying how specific diets can help abalones survive better in high-temperature conditions, which are tough for their cultivation. Furthermore, the introduction of good bacteria (probiotics) has proven to boost abalones’ immune systems, aiding in their defense against bacterial threats and ultimately promoting the longevity of abalone farming. To promote eco-friendly practices in abalone cultivation, experts are exploring the use of a mix of seaweed types as a substitute for fish feed, reducing the need for fish-based feeds and improving the overall environmental impact of abalone farming. Moreover, repurposing abalone shells, a byproduct of the industry, for making biocompatible materials for drug delivery systems showcases an innovative approach to supporting environmental sustainability. These research findings underline the health advantages of consuming abalone and the continuous efforts to ensure its eco-friendly production and utilization.
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