🤔 Q: Why is only about 10% of energy transferred from one trophic level to another? Why not all of it?

 

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🤷‍♀️สงสัยจัง! ทำไมพลังงานถึงถ่ายทอดไปแค่ 10%?

(ทำไมพลังงานถึงถ่ายทอดจากระดับโภชนาการหนึ่งไปยังอีกระดับหนึ่งเพียง 10%? ทำไมไม่ทั้งหมดล่ะ?)

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💡 A: The Mystery of the Missing Energy! ไขปริศนาพลังงานที่หายไป! 🕵️‍♂️

Hey there! Great question! It's a super important concept in understanding how ecosystems work. Let's break down why so much energy seems to "disappear" as it moves up the food chain. สวัสดีค่ะ! เป็นคำถามที่ดีมากเลยค่ะ! มันเป็นแนวคิดที่สำคัญมากในการทำความเข้าใจการทำงานของระบบนิเวศ เรามาดูกันว่าทำไมพลังงานจำนวนมากถึงดูเหมือน "หายไป" เมื่อมันเคลื่อนที่ขึ้นไปตามห่วงโซ่อาหาร

The short answer is that organisms use up most of the energy they consume for their own life processes, and a lot is lost as heat! 😊

คำตอบสั้นๆ คือ สิ่งมีชีวิตใช้พลังงานส่วนใหญ่ที่บริโภคเข้าไปเพื่อกระบวนการดำรงชีวิตของตัวเอง และพลังงานจำนวนมากจะสูญเสียไปในรูปของความร้อน!

The Journey of Energy: From Sun to Predator (การเดินทางของพลังงาน: จากดวงอาทิตย์สู่ผู้ล่า) ☀️➡️🌿➡️🐇➡️🦊

First, remember that energy flows unidirectionally (ไหลทิศทางเดียว) through ecosystems. The ultimate source for most life on Earth is the sun (ดวงอาทิตย์) (Wikipedia contributors, n.d.-b).

1. Producers (ผู้ผลิต): Plants (พืช), algae (สาหร่าย), and some bacteria capture this solar energy via photosynthesis (การสังเคราะห์ด้วยแสง), converting it into chemical energy (like sugars) stored in their bodies (NEXT IAS Team, 2024). They are the starting point!
2. Consumers (ผู้บริโภค): When an herbivore (สัตว์กินพืช) eats a plant, or a carnivore (สัตว์กินเนื้อ) eats an herbivore, that chemical energy is transferred. This happens through food chains (ห่วงโซ่อาหาร – a straight line of who eats whom) and more complex food webs (สายใยอาหาร – interconnected chains) (Singh, n.d.).

The "10% Rule": A General Guideline (กฎ 10%: แนวทางทั่วไป) 📏

The transfer of energy between these trophic levels (ระดับโภชนาการ – feeding levels) is surprisingly inefficient.

• On average, only about 10% of the total energy available at one trophic level gets passed on to the next (TutorChase, n.d.). This is famously known as the "10% rule" or the "ten percent law."
• It's important to note that this is an average. The actual Trophic Level Transfer Efficiency (TLTE) can range from about 5% to 20%, depending on the specific ecosystem and the organisms involved (Boundless, n.d.; McIvor, 2024).

So, if a plant has 1000 Joules of energy, the herbivore that eats it might only get about 100 Joules stored in its body. And a carnivore eating that herbivore might only get 10 Joules! 📉

So, Where Does All That Energy Go? (แล้วพลังงานทั้งหมดหายไปไหน?) 💨🔥🦴💩

Here are the main reasons why 100% of the energy doesn't make it to the next level (Mani Kanth, 2018; McIvor, 2024):

1. Metabolic Processes & Heat Loss (กระบวนการเผาผลาญและการสูญเสียความร้อน) 🔥:
• Organisms are busy! They use a HUGE chunk of the energy they consume just to stay alive. Think about:
• Respiration (การหายใจ): Converting food into usable energy.
• Movement (การเคลื่อนไหว): Running, flying, swimming, even just moving leaves.
• Maintaining Body Heat (การรักษาอุณหภูมิร่างกาย): Especially for warm-blooded animals (endotherms - สัตว์เลือดอุ่น) like birds and mammals. They use a lot more energy to keep warm compared to cold-blooded animals (ectotherms - สัตว์เลือดเย็น) like insects or fish (Boundless, n.d.).
• A fundamental principle in physics (the second law of thermodynamics) tells us that whenever energy is converted from one form to another, some of it is lost as heat to the environment. This metabolic heat isn't usable by the next trophic level.
2. Growth and Reproduction (การเจริญเติบโตและการสืบพันธุ์) 🌱➡️👶:
• Some energy goes into building new tissues (growing bigger) and creating offspring. Only the energy that becomes biomass (ชีวมวล – the actual body material) is potentially available for the next level to eat.
3. Uneaten Parts (ส่วนที่ไม่ได้กิน) 🦴🪵:
• Predators don't usually eat every single bit of their prey. Bones, fur, feathers, shells, roots, or tough woody stems often get left behind. The energy stored in these parts isn't transferred.
4. Incomplete Digestion & Waste (การย่อยไม่สมบูรณ์และของเสีย) 💩:
• Even the parts that are eaten might not be fully digestible. The energy in undigested food is expelled as waste products like faeces (อุจจาระ) and urine (ปัสสาวะ). This energy is lost to the consumer.
5. Non-Predatory Death (การตายโดยไม่ได้ถูกล่า) 💀🍂:
• Some organisms die from disease, accidents, or old age before they get eaten. Their energy then goes to decomposers (ผู้ย่อยสลาย – like bacteria and fungi) rather than up the main food chain to higher consumers.

Net Production Efficiency (NPE) (ประสิทธิภาพการผลิตสุทธิ) 📊

Scientists use a measure called Net Production Efficiency (NPE) to describe how efficiently organisms at one trophic level convert the energy they receive into biomass that's then available to the next level. It considers energy lost through incomplete eating, respiration, and waste (Boundless, n.d.).

Why This Matters: Limits on Food Chains (ทำไมสิ่งนี้ถึงสำคัญ: ข้อจำกัดของห่วงโซ่อาหาร) ⛓️

This massive energy loss at each step is the reason why food chains are usually quite short – typically no more than 4 to 6 trophic levels (NEXT IAS Team, 2024). There's simply not enough energy left to support viable populations at very high trophic levels. The closer an organism is to the producer level, the more energy is available to it.

In a nutshell (สรุปง่ายๆคือ): Most of the energy an organism gets is used to live, move, and keep warm, or it's in parts that don't get eaten or can't be digested. Only a tiny fraction becomes "meat on the bones" (biomass) for the next predator. This is why the 10% rule is a key concept in ecology! 🌿➡️🐇 (100%) ➡️ 🦊 (10%) ➡️ 🦅 (1%).

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Further Thought (คิดต่อยอด) 🤔:

Given these variations, it could be interesting to compare the ecological efficiency (percentage of energy transferred) in different environments, like aquatic (ในน้ำ) vs. terrestrial (บนบก) ecosystems, and explore what makes them different!

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Bibliography: บรรณานุกรม 📚

Boundless. (n.d.). 46.2C: Transfer of Energy between Trophic Levels. Biology LibreTexts. Retrieved from https://bio.libretexts.org/@go/page/14227

Mani Kanth. (2018, April 16). Energy flow in ecosystem [PPT]. SlideShare. https://www.slideshare.net/ManiKanth/energy-flow-in-ecosystem-96048230

McIvor, L. M. (2024, November 21). Efficiency of Energy Transfer (Cambridge (CIE) IGCSE Co-ordinated Sciences (Double Award): Revision Note). Save My Exams. Retrieved from https://www.savemyexams.co.uk/gcse/coordinated-science-cie/revision-notes/18-organisms--their-environment/energy--feeding-relationships/efficiency-of-energy-transfer/

NEXT IAS Team. (2024, August 17). Energy Flow in Ecosystem: Food Chain, Food Web & More. NEXT IAS. https://www.nextias.com/blog/energy-flow-in-ecosystem

Singh, A. K. (n.d.). FOOD CHAINS AND FOOD WEBS. Dr. Shyama Prasad Mukherjee University. Retrieved from https://drspsmu.ac.in/wp-content/uploads/2020/05/Food-Chains-and-Food-Webs.pdf

TutorChase. (n.d.). What is the 10% rule in energy transfer between trophic levels? Retrieved from https://www.tutorchase.com/answers/ib/biology/what-is-the-10-rule-in-energy-transfer-between-trophic-levels

Wikipedia contributors. (n.d.-a). Bioaccumulation. In Wikipedia. Retrieved October 26, 2024, from https://en.wikipedia.org/w/index.php?title=Bioaccumulation&oldid=1291696167 (Note: While "Bioaccumulation" is in the list, the primary focus of this answer is energy flow; including for completeness of provided bibliography.)

Wikipedia contributors. (n.d.-b). Energy flow (ecology). In Wikipedia. Retrieved October 26, 2024, from https://en.wikipedia.org/w/index.php?title=Energy_flow_(ecology)&oldid=1292001618

(Note: The Purdue University & USEPA Region 5 citation was omitted as it pertains specifically to bioaccumulation, not directly to the 10% energy transfer rule explained here, though it was in your provided list.)

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