Internal Insect Morphology

00:06:40
https://www.youtube.com/watch?v=RWMh3HXV60s

概要

TLDRIn this comprehensive video, Dr. DeBusk explores the internal morphology of insects, focusing on their digestive, circulatory, nervous, respiratory, and reproductive systems. The digestive system consists of the foregut (for initial food processing), midgut (primary digestion and absorption), and hindgut (water reabsorption and waste excretion). The circulatory system is open, with hemolymph circulating freely and containing no hemoglobin. The nervous system allows insects to respond to stimuli, suggesting they may feel pain. Their respiratory system relies on spiracles and trachea for gas exchange, and insects can hold their breath for extended periods to manage oxygen levels. Reproductive systems in insects vary significantly, with females able to store sperm and produce eggs, while males generate sperm through their testes. Overall, the video underscores that while insect systems are less complex than those of humans, they serve crucial and specialized functions within each organism.

収穫

  • 🦗 Insects have a long digestive tract with foregut, midgut, and hindgut.
  • 🩸 Insect blood, called hemolymph, flows freely in an open circulatory system.
  • 🧠 Insects possess a nervous system similar to humans, allowing for sensory responses.
  • 🌬️ Insects breathe through spiracles and can hold breath for hours or days.
  • 🧬 Reproductive systems in insects show significant variation among species.

タイムライン

  • 00:00:00 - 00:06:40

    In this video, Dr. DeBusk explores the internal morphology of insects, answering common questions about their biology. The digestive system consists of the foregut, midgut, and hindgut, with each section serving specific functions in digestion, nutrient absorption, and waste excretion. The foregut begins the food breakdown process, the midgut is the primary site for digestion, and the hindgut reabsorbs water and excretes waste. Key structures such as gastric caecae and Malpighian tubules assist in nutrient absorption and osmoregulation respectively, while the insect circulatory system, characterized as open, involves hemolymph flowing freely in the body. The nervous system is similar to that of humans, allowing insects to experience sensations, including pain. Additionally, the respiratory system consists of tracheal tubes for gas exchange, enabling some insects to hold their breath. Finally, the reproductive systems vary among species but generally include ovaries and testes, indicating less complexity compared to human anatomy. Overall, insects have distinct internal processes that reflect their adaptation and survival in various environments.

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ビデオQ&A

  • What is the yellow stuff that squirts out of an insect when stepped on?

    It is likely the hemolymph, which is the insect's blood that contains nutrients and waste.

  • Do insects feel pain?

    Yes, insects have a nervous system and respond to various sensations, suggesting they probable feel pain.

  • Can an insect hold its breath under water?

    Yes, some insects can hold their breath for hours or even days, controlling their spiracles to regulate gas exchange.

  • What does the digestive system of an insect consist of?

    It consists of three parts: foregut, midgut, and hindgut, each serving distinct functions in digestion and absorption.

  • How does the insect circulatory system work?

    Insect circulatory systems are open, with hemolymph flowing freely throughout the hemocoel, pumped by the dorsal vessel.

  • What are Malpighian tubules?

    Malpighian tubules are structures that help with osmoregulation and excretion, located near the midgut and hindgut junction.

  • What substances do the accessory glands produce?

    They produce substances that help package and lay the eggs in female insects.

  • What is hemolymph?

    Hemolymph is the insect equivalent of blood, transporting nutrients and wastes, and is about 90% water.

  • How do insect reproductive systems vary?

    They can vary greatly among closely related species, often having small morphological differences that prevent interspecies mating.

  • What is the primary function of the midgut?

    The midgut is the major area for digestion and absorption of nutrients.

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  • 00:00:00
    What’s that yellow stuff that squirts out of an insect when you step on it? Do insects
  • 00:00:05
    feel pain? Can an insect hold its breath under water? These are all common questions when
  • 00:00:11
    it comes to the internal workings of an insect and you will find out the answers to these
  • 00:00:15
    before the end. By the way, I’m more of a catch in a cup and release type of girl
  • 00:00:21
    than a step and squish person. Just saying. I’m Dr. DeBusk and in this video, I’m
  • 00:00:27
    going to talk about the internal morphology of insects.
  • 00:00:31
    The digestive system (sometimes referred to as the alimentary canal) is a long tube-like
  • 00:00:36
    structure that runs from the mouth to the anus and is centrally located within the body
  • 00:00:40
    cavity, or hemocoel. The anterior-most region is called the foregut (or stomodeum) which
  • 00:00:47
    includes the buccal cavity, the esophagus, and the crop which stores food. The primary
  • 00:00:53
    function of the foregut is to begin the breakdown of food particles and transport them to the
  • 00:00:58
    next region, the midgut (or mesenteron). In some insects, the crop opens into a muscular proventriculus.
  • 00:01:06
    This organ contains tooth-like denticles that grind and pulverize food particles. The proventriculus
  • 00:01:12
    serves much the same function as a gizzard in birds.  The midgut is the major area of
  • 00:01:17
    digestion and absorption. Undigested food particles then pass into the third region,
  • 00:01:23
    the hindgut (or proctodeum), which consists of the ileum, colon, rectum, and (often) rectal
  • 00:01:30
    pads. The hindgut functions in water and solute reabsorption and waste excretion. The three
  • 00:01:36
    sections of the digestive tract can be easily identified by structures found at the junction
  • 00:01:41
    of each region. Gastric caecae, for example, mark the end of the foregut and beginning
  • 00:01:46
    of the midgut. It is believed that the purpose of these structures is to increase surface
  • 00:01:51
    area for greater nutrient absorption. The constriction at the gastric caecae also marks
  • 00:01:56
    the spot of the cardiac valve (or sphincter). Near the junction of the midgut and hindgut
  • 00:02:02
    are long, thin structures called Malpighian tubules. These range in number from a few
  • 00:02:06
    to hundreds, but only aphids (Order Hemiptera) are currently known to have none. Malpighian
  • 00:02:12
    tubules are creamy to yellow in color and work in conjunction with the ileum to provide
  • 00:02:17
    the primary site for osmoregulation and excretion. Unlike the “closed” circulatory system
  • 00:02:24
    of humans, insect circulatory systems are said to be “open”, meaning that they lack
  • 00:02:29
    a complex network of veins and arteries to help transport blood throughout the body.
  • 00:02:34
    Instead, insect blood (called hemolymph) flows relatively “freely” throughout the hemocoel.
  • 00:02:41
    Only one vessel is present in the insect circulatory system: the dorsal vessel. Posteriorly (in
  • 00:02:47
    the abdominal region), the dorsal vessel acts as the heart, pumping hemolymph forward into
  • 00:02:54
    the anterior region (in the head and thorax), where it acts as the aorta and dumps the hemolymph
  • 00:03:00
    into the head. It flows posteriorly and is returned to the heart via ostia, which are
  • 00:03:07
    small slits in the heart region of the dorsal vessel designed for hemolymph uptake. The
  • 00:03:12
    hemolymph is approximately 90% water, straw-colored, yellow or green, without any hemoglobin since
  • 00:03:18
    it is not involved in respiration. It transports nutrients and wastes to and from the organs
  • 00:03:23
    and tissues. It will temporarily store and convert trehalose, a type of sugar broken
  • 00:03:29
    down for energy. It also creates hydraulic pressure needed in molting and hatching.
  • 00:03:35
    The ventral nerve cord resembles a railroad track running from the head posteriorly to
  • 00:03:41
    the abdominal region. The “railroad track” is made up of two nerve cords (connectives)
  • 00:03:47
    that run longitudinally with a series of node-like ganglia. The anterior most region of the ventral
  • 00:03:54
    nerve cord is called the subesophageal ganglion. Just dorsal to that structure is the insect
  • 00:04:01
    “brain.” So do insects feel pain? Insects have a nervous system that resembles ours in many
  • 00:04:06
    ways. That is, they see, hear, smell, taste, and feel. Many of our pains arise from pressure,
  • 00:04:13
    shock, heat and other stimuli administered at high levels—and insects most assuredly
  • 00:04:18
    respond to these bodily sensations. So, yeah, probably.
  • 00:04:23
    The insect respiratory system is made up of a series of tubes that originate from spiracles
  • 00:04:28
    (openings of the exoskeleton that allow for gas exchange) and extend throughout the body.
  • 00:04:33
    Internally, the tubes, or trachea, appear as thin white lines throughout the hemocoel
  • 00:04:40
    and are particularly noticeable surrounding internal organs. Trachea deliver oxygen to
  • 00:04:45
    internal organs and tissues through the tracheoles. So can insects hold their breath? Even though
  • 00:04:51
    insects breathe through spiracles not their mouth, scientists have known that some insects
  • 00:04:57
    can hold their breath for hours or even days. Studies suggest that while oxygen is vital to an insect,
  • 00:05:03
    too much can damage tissue. The opening and closing of spiracles is controlled in a way
  • 00:05:08
    that exhales carbon dioxide as needed without inhaling too much oxygen. So if you are trying
  • 00:05:14
    to drown a roach, you may be waiting for a while.
  • 00:05:18
    Variation among insect reproductive systems is great. Closely related species are often
  • 00:05:23
    isolated from one another via small variations in the morphology of reproductive organs that
  • 00:05:28
    prohibit interspecies mating. However, a generalized system can be constructed that closely represents
  • 00:05:35
    all sexually reproducing insects. Female insects are able to make eggs, receive and store sperm,
  • 00:05:41
    manipulate sperm from different males, and lay eggs. Their reproductive systems are made
  • 00:05:46
    up of a pair of ovaries, accessory glands, one or more spermathecae, and ducts connecting
  • 00:05:51
    these parts. The ovaries make eggs and accessory glands produce the substances to help package
  • 00:05:57
    and lay the eggs. Spermathecae store sperm for varying periods of time and, along with
  • 00:06:03
    portions of the oviducts, can control sperm use. The main component of the male reproductive
  • 00:06:08
    system is the testis, suspended in the body cavity by tracheae and the fat body. Most
  • 00:06:14
    male insects have a pair of testes, inside of which are sperm tubes or follicles that
  • 00:06:19
    are enclosed within a membranous sac. The terminal portion of the ejaculatory duct may
  • 00:06:24
    be sclerotized to form the aedeagus. So there you have it. The internal systems of
  • 00:06:29
    an insect in many ways is different than a human and you can see that they are not particularly
  • 00:06:34
    complex. I hope you learned something about the internal systems of insects.
タグ
  • insect anatomy
  • digestive system
  • circulatory system
  • nervous system
  • respiratory system
  • reproductive system
  • hemolymph
  • Malpighian tubules
  • spiracles
  • pain in insects