Lobsters are fascinating creatures that have captured the attention of seafood lovers and marine biologists alike. But did you know that lobsters are cold-blooded?
This means that their body temperature is determined by the temperature of the water they live in. As ocean temperatures continue to rise due to climate change, the impact on these crustaceans could be significant.
In this article, we’ll explore the unique physiology of lobsters and how their cold-blooded nature affects their behavior, diet, and survival. So, let’s dive in and learn more about these fascinating creatures!
Are Lobsters Cold Blooded?
Yes, lobsters are cold-blooded animals. This means that they cannot regulate their body temperature internally, unlike warm-blooded animals such as mammals and birds. Instead, their body temperature is determined by the temperature of the water they live in.
As the water temperature rises, so does the temperature of a lobster’s blood. This can have significant impacts on their behavior and physiology. For example, higher temperatures can cause lobsters to use more energy for respiration, leaving less energy for feeding, growth, and reproduction. It can also affect their immune response and migration patterns.
Furthermore, studies have shown that lethal temperatures for lobsters range from 75-86 degrees Fahrenheit. As coastal waters continue to warm due to climate change, this could pose a significant threat to lobster populations.
The Physiology Of Lobsters
Lobsters have a unique physiology that allows them to survive in their marine environment. They have a long, segmented exoskeleton made of chitin that protects them from predators and provides support for their muscles. Their ten legs, with one or more pairs modified into pincers (chelae), are jointed and provide the lobster with a wide range of movement.
As invertebrate crustaceans, lobsters lack an internal skeleton or bones. Instead, they have a hard outer shell or exoskeleton that they must periodically shed in order to grow. The lobsters’ nervous system is primitive and similar to that of an insect, lacking a brain and consisting of only approximately 100,000 neurons.
Lobsters have a circulatory system that is responsible for transporting oxygen and nutrients throughout their body. Their blood is usually greyish/clear in color and is circulated by a heart located just behind the stomach. Oxygen is picked up from the water through the gills, which are located in the lobsters’ thorax section.
The lobsters’ digestive system consists of a mouth, stomach, and intestines. They are omnivorous and feed on a variety of prey including fish, crabs, clams, and other shellfish. Lobsters are also known for their strong immune system, which helps protect them from diseases and parasites.
In terms of metabolism, lobsters have a standard metabolic rate that increases with higher temperatures. This means that they require more energy to survive in warmer waters. When threatened by predators, lobsters may display anti-predator responses such as immobility or ‘freezing’. However, studies have shown that warmer temperatures may induce changes to these typical predator-risk responses.
Cold-Blooded Vs. Warm-Blooded Animals
Cold-blooded and warm-blooded animals are two distinct categories of animals that differ in how they regulate their body temperature. Cold-blooded animals, such as reptiles, fish, and amphibians, cannot produce their own body heat and rely on the environment to regulate their body temperature. In contrast, warm-blooded animals, such as mammals and birds, can generate their own body heat to maintain a constant internal body temperature.
The ability to regulate body temperature has significant impacts on an animal’s behavior, physiology, and distribution. For example, cold-blooded animals are more active in warmer temperatures when their metabolism is higher, while warm-blooded animals can maintain activity levels in a wider range of temperatures.
Additionally, warm-blooded animals are better equipped to fight off infections and diseases since their constant body temperature provides a perfect incubator for germs. In contrast, cold-blooded animals have a lower risk of infection due to their inability to cultivate germs easily.
How Lobsters Regulate Their Body Temperature
Lobsters are unable to regulate their body temperature metabolically, meaning that they rely on their environment to control their body temperature. This process is known as poikilothermy. Lobsters have a remarkable ability to maintain homeostasis and metabolism during long-term thermal acclimatization or acclimation. They can acclimate and survive at temperatures ranging from −1.0°C to 30.5°C.
Despite being unable to regulate their body temperature, lobsters are able to adapt to different temperatures in their environment. They are known to be active and even mate at temperatures in the 0-2°C range, and individuals that reach premolt before declining autumn temperatures may continue the molting process, eventually shedding the exoskeleton at temperatures as low as 0°C.
Studies have also shown that lobsters can adjust their acid-base status in response to changes in temperature. For example, when exposed to acute increases in temperature, lobsters trigger a respiratory compensated metabolic acidosis of the hemolymph. Additionally, changes in acid-base status triggered by thermal variations in the environment might modulate lobster cardiac performance in vivo.
The Impact Of Climate Change On Lobsters
Climate change is having a significant impact on lobsters and the fishing industry that relies on them. Warmer sea surface temperatures are forcing lobsters to migrate to higher latitudes than ever before, disrupting fishing communities on the New England coast. The Gulf of Maine, where the lobster industry generates $1.4 billion and employs thousands of people, is warming faster than 99% of the global oceans. This is causing lobsters to move to deeper and colder waters, making it more difficult for fishermen to catch them.
Additionally, warming waters are causing lobsters to shed their shells earlier than usual, which can disrupt the usual flow of lobsters to market. This can have significant economic impacts on the fishing industry as well.
Furthermore, as lobsters are cold-blooded animals, they cannot regulate their body temperature internally. As the water temperature rises, so does the temperature of their blood. This can cause significant impacts on their behavior and physiology, such as affecting their energy use, immune response, and migration patterns.
If coastal waters continue to warm due to climate change, it could pose a significant threat to lobster populations. Lethal temperatures for lobsters range from 75-86 degrees Fahrenheit, which means that continued warming could have dire consequences for the lobster industry and the ecosystem they inhabit.
Lobsters’ Behavior And Diet In Relation To Their Cold-Blooded Nature
Lobsters’ cold-blooded nature also affects their behavior and diet. As mentioned earlier, lobsters are more active and hunt for food at night when the water temperature is cooler. They are opportunistic feeders, catching mainly fresh food such as fish, crabs, clams, mussels, and sea urchins. They are also cannibalistic and will sometimes eat other lobsters.
Lobsters use their four small antennules and tiny sensing hairs to “smell” their food. They use their crusher claw to break open shellfish and their ripper claw to tear food apart. The two sets of walking legs behind the claws are also used for catching and eating food and have many “taste” sensors.
Interestingly, lobsters’ teeth are in their stomachs, which are located a short distance from their mouths. The food is actually chewed in the stomach between three grinding surfaces called the gastric mill.
In terms of behavior, lobsters use chemical signals to form and maintain dominance hierarchies, choose and locate mates, determine reproductive receptivity, recognize individual conspecifics, and perhaps regulate their molt cycles. These chemical signals are carried primarily in urine and dispersed into the environment by animal-generated currents.
Additionally, healthy lobsters have been observed to stay away from others that are sick with a deadly virus, indicating a level of social behavior and awareness.
Lobsters’ Survival In Changing Ocean Temperatures
The survival of lobsters is closely tied to the temperature of the water they live in. Research has shown that rising sea surface temperatures due to climate change are forcing populations of the American lobster to higher latitudes than ever before. In the Gulf of Maine, water temperatures have been warming seven times faster than the average global increase in ocean temperatures between 2004 and 2013. This rapid increase has resulted in higher mortality rates and fewer surviving offspring in cod stocks, and there are concerns there will be similar effects on the lobster population.
A new study by scientists in Maine found that if global warming trends continue, lobsters will struggle to survive by the year 2100. The study found that lobster larvae struggled to survive when they were reared in water five degrees Fahrenheit warmer than the temperatures that are currently typical of the western Gulf of Maine, a key lobster fishing area off of New England. Five degrees is how much the United Nations’ Intergovernmental Panel on Climate Change expects the Gulf of Maine’s temperature to warm by the year 2100. The paper appears this month in the scientific journal ICES Journal of Marine Science.
The study’s authors found higher temperatures caused baby lobsters to develop faster – something that could help them avoid predators in the wild – but few survived. Disease is also more common in lobsters when ocean water temperatures rise, which is currently the problem in the Gulf of Maine. Lobsters are already starting to catch a new disease called paramoebiasis, a parasite that invades the nervous tissue and causes death of the lobster. Lobsters typically start to catch this disease after long stretches of above-average temperatures.
The changing ocean temperatures are also affecting the productivity of the Gulf of Maine ecosystem. The influence of the cold, nutrient-rich Labrador Current from the north is diminishing, while the warm, salty and nutrient-poor Gulf Stream waters are being felt more strongly. Researchers hypothesize that these changes, along with the adverse effects of stressful warm summer temperatures, have caused a decline in larval lobster survival that ultimately results in smaller harvests.
