Are Lobsters Cold Blooded? A Look at How Temperature Impacts These Crustaceans

Lobsters are one of the most iconic seafoods, loved for their sweet meat and ability to thrive in cold northern waters But an interesting fact many people don’t know is that lobsters are cold blooded animals Their body temperature is regulated by their external environment.

So how exactly does being cold blooded impact lobsters and their behavior? Let’s take a closer look at some of the key effects water temperature has on these fascinating crustaceans,

What Does Cold Blooded Mean?

Cold blooded animals, also known as ectotherms, are unable to internally regulate their own body temperature like humans can. Instead, the temperature of their blood and tissues is determined by their external environment.

When the external temperature is cold, a cold blooded animal’s body temperature drops. And when the environment is warm, their body temperature rises. This is in contrast to warm blooded (endothermic) animals like mammals and birds that maintain a consistent internal body temperature.

For aquatic animals like lobsters that live in the frigid northern Atlantic and Pacific oceans, water temperature has a significant influence over their physiology and behavior Even small changes in water temperature can impact their distribution, growth rate, metabolism, reproduction, and more.

Understanding how fluctuations in water temperature affect lobsters is crucial for lobstermen and scientists studying these creatures in the context of a changing climate.

How Do Lobsters React to Changing Water Temperatures?

Lobsters prefer water temperatures between 12-18°C (54-64°F), with their growth and metabolism optimal between 15-20°C (59-68°F). But as cold blooded organisms, what happens when the water temperature goes outside this preferred range?

Warmer Water

• Lobsters become more active and feed more frequently. But their appetite decreases above 20°C (68°F).

• Warmer water increases their metabolism, requiring more energy expenditure. This leaves less energy available for growth and reproduction.

• Above 23°C (73°F) severe stress occurs, limiting oxygen delivery to tissues.

• Once water reaches 30°C (86°F) it becomes fatal.

Colder Water

• Lobsters become dormant and stop eating as metabolism slows. But they can survive extended periods in near freezing water.

• Movement and responses are sluggish. But shelter-seeking increases.

• Growth and molting frequency decline or stop completely until warming occurs.

• Reproduction ceases as maturity and spawning are delayed. Egg development is slowed.

So in their ideal temperature range, lobsters are most active, growing quickest, and reproducing most successfully. But as waters warm or cool outside this zone, lobsters become stressed and their normal functioning is impaired.

How Is Climate Change Impacting Lobsters?

Over the past several decades, ocean temperatures in the Northwest Atlantic have been increasing. This is tied to climate change causing overall warming of ocean waters globally.

For American lobsters that thrive in the cold waters off New England and Atlantic Canada, what does this progressive warming mean?

Some impacts researchers have observed include:

• Expansion northward into colder waters like the Gulf of Maine and Gulf of St. Lawrence.

• Declines in populations at the southern edge of their range due to heat stress.

• Increased growth and molting rates in the newly warmer waters.

• Earlier timing of larval release and peak landings.

• Boom in populations and catch rates in the Gulf of Maine as waters reached optimal temperatures.

However, scientists warn rising temperatures could eventually exceed lobsters’ thermal limits throughout their range. And other climate impacts like ocean acidification and declining oxygen could add further stress to lobster populations.

Researchers are working to develop models to predict whether continued warming will allow current lobster fishing grounds to remain productive, or if the optimal temperatures for lobsters will eventually shift into Canada’s maritime provinces.

Can Lobsters Adapt to Warming Waters?

Lobsters have survived over millions of years, adapting as ocean conditions changed. But are they equipped to handle today’s rapid pace of climate change?

Unfortunately, biological adaptation for poikilotherms like lobsters can take decades to centuries to occur. Some research suggests limits to lobsters’ abilities to adapt to warming waters:

• Larvae develop optimally within an extremely narrow temperature band – implications for reproduction.

• High genetic similarity observed over a large geographic range – less diversity for natural selection.

• Slow growth to maturity (5-8 years) limits pace of adaption across generations.

While lobsters may exhibit some microevolutionary changes like earlier larval development, the swift pace of current ocean warming may outstrip their capacity to adapt through natural selection.

However, the full range of lobsters’ adaptive capabilities isn’t conclusively known. Scientists continue working to understand whether lobsters can successfully adapt to avoid collapse of this economically crucial fishery.

The Takeaway on Lobsters and Temperature

Lobsters perfectly exemplify the sensitivities of cold blooded creatures. They thrive within a specific environmental niche of deep, cold-water habitats. Even subtle temperature changes influence their metabolism, growth, reproduction, behavior, and more.

As ocean waters rapidly warm, researchers are concerned that temperatures could soon exceed physiological thresholds for lobsters, especially for larvae. This could spell trouble for lobster populations and the fishermen who rely on them for their livelihoods.

Understanding the impacts of rising ocean temperatures will help predict future trends in lobster supply and distribution. And shed light on how vulnerable cold blooded marine species may fare as climate change alters their ocean ecosystems.

So while the dramatic effects of warming waters on lobsters highlight the perils of climate change, they also underscore the urgent need to limit emissions and help cold blooded creatures adapt however we can.