Spiny dogfish have been present in oceans for millions of years. Sailors have numerous interesting stories about them. This article will teach you about such stories and some interesting facts about what kind of fish the spiny dogfish is. Moreover, it is also interesting to know about the spiny dogfish’s size, its feeding habits, and its relationship with other fish and humans. In addition, if you want to learn whether you can keep them in a home tank or not, scroll down the page.
Content Table
spiny dogfish
Spiny Dogfish
Spiny dogfish are unique marine fish that live in the temperate and subarctic waters of the North Atlantic and North Pacific Oceans. They are small schooling sharks with numerous unique features. For example, they have two dorsal fins, which is a rare feature. Here is the profile of the spiny dogfish.
Profile
| Feature | Description |
| Phylum | Chordata |
| Class | Chondrichthyes |
| Family | Squalidae |
| Genus | Squalus |
| Species | About 40 |
| Scientific Name | Squalus acanthias |
| Species | Approximately 40 |
| Common Names | Spiny dogfish |
| Blue dog | |
| Piked dogfish | |
| Mud shark | |
| Spurdog | |
| Body type | Cylinder, elongated, and pointed snot |
| Size | Male: 24–35 inches |
| Female: 30–42 inches | |
| Weight | 7 to 10 pounds |
| Lifespan | 30 to 80+ years |
| Spines | 2 dorsal fins |
| Coloration | Gray to brown above, light bottom, and tiny white spots on the sides |
| Tooth Structure | Small, sharp, and overlapping cusps |
| Diet | Carnivorous |
| Social structure | Schooling |
| Reproduction | Ovoviviparous, i.e., give birth to live fish |
| Gestation period | 18 to 24 months |
What Do Spiny Dogfish Eat?
Spiny dogfish are carnivores and feed on small to medium-sized, diverse prey in water. Here are different diet options that spiny dogfish love to consume.
Carnivores Food
| Type | Options | |||
| Fish | Herring | Flatfish | Cod | Menhaden |
| Sand lance | Haddock | Mackerel | Capelin | |
| Invertebrates | Crabs | Octopus | Shrimp | Squid |
| Jellyfish | sea cucumbers | |||
| Random feeding | Dead fish | |||
Feeding Method
They prey on small to medium-sized fish and other invertebrates in a group. They use their cerated teeth to tear apart their prey with almost 20N force.
Food Chain
Spiny dogfish are tertiary consumers at the food chain level. They play a pivotal role in the population control of small or medium-sized fish and other invertebrates. Here is the food chain detail.
Base Level
This level has Phytoplankton and algae. They gain energy by capturing the sunlight.
Primary Consumers
Primary consumers of the spiny dogfish food chain include zooplankton and small crustaceans. They consume phytoplankton and algae.
Secondary Consumers
The secondary level consists of small schooling fish, squid, and shrimps. These small to medium-sized fish and invertebrates feed on zooplankton, i.e., primary consumers.
Tertiary Consumers
At this level, spiny dogfish prey on secondary consumers, small or medium fish, squids, and invertebrates.
Higher-Level Consumer
Spiny dogfish are the food for large predators. Large predators include the following.
- Large sharks
- Killer whales
- Seals
- Sea lions
- Human
How Big of It?
They are at 3.77 to 4.15 on the trophic level scale. Plants are considered 1 at this scale, and apex predators are 5.
What kind of fish is the spiny dogfish
Are Spiny Dogfish Friendly?
If you want to keep them as aquatic pets, they are not friendly to other aquatic pets, as they love to eat small to medium fish. Moreover, they are aggressive and in danger; they attack the predator with venom that is present in their spine.
Characteristics
- They are considered small sharks with a size of up to 5 feet.
- They secrete mild venom under threat. Although venom is not deadly, it can cause painful wounds.
- Spiny Dogfish are schooling and traveling in a large school.
- They are curious about humans.
Are Spiny Dogfish Aggressive or Friendly?
They are not as friendly as dolphins, but also not super aggressive. They treat humans and small to medium-sized fish in a separate manner.
Humans
They are curious about humans. They don’t attack swimmers and divers in oceans. They have a venomous spine, which they use when they feel threatened. However, they prefer to flee rather than fight with humans.
Fish and Other Invertebrates
They efficiently prey on small fish and other invertebrates. Although they are opportunistic and persistent predators, they don’t harass them for eating.
In Aquariums
Due to their large size, aggressiveness, and schooling behavior, they are not suitable for home aquariums. However, they can live in large public aquariums.
Precautions for Large Aquariums
Here are precautions for large public aquariums.
- Keep them in a group.
- Fulfill their feeding requirements.
- Handle them gently, as they can attack when they sense a threat.
spiny dogfish size
Is There a Way to Keep Small Spiny Dogfish Safely at Home?
It is nearly impossible to keep a spiny dogfish in a home aquarium. Here are various reasons.
Size and Space
Home aquariums are small to keep spiny dogfish. On average, one individual can grow up to 4 feet, and they live in a group. They are active. For these reasons, it is hard to keep them in home aquariums.
Environmental Requirements
They do well in cold, i.e., 5–15 °C, require a high oxygen level, and a heavy filtration system to manage their bioload. These things are also hard to provide in a home aquarium. If provided, difficult to manage.
Feeding
They require a large, frequent, and protein-rich diet that affects the water quality.
Other Issues
Spiny dogfish are hard to manage due to their venomous spine. A small space also puts them under stress that can cause diseases. Moreover, they live up to 80 years. So, a long commitment is required to manage them in aquariums.
Anecdote About Spiny Dogfish
- They are named spiny dogfish as they prey and live in packs like dogs.
- Some sailors also call them “sea wolves”.
- Fishermen can get the entire pack within minutes as they move together toward the bait.
- It is an old joke about a spiny dogfish pregnancy ‘longer than a sailor’s voyage.’
- They are considered a curse in the North Atlantic Ocean. Fishermen said about them, “a curse, a dozen a plague, and a hundred the end of fishing for the day”.
- Some sailors made sewing needles from the dried spines, even though they are venomous. Their venom can numb the sailor’s hand for hours to months.
- During WW2, they were sold in England as “Rock Salmon” or “Huss”. It was done to overcome the food shortage.
- Old Britons call them a “secret shark meet” to feel nostalgia.
What do spiny dogfish eat
Interesting Facts Related to Spiny Dogfish
Here are some interesting facts about spriny dogfish.
- They live in a group. This group can comprise thousands of individual spiny dogfish.
- They carry one of the longest pregnancies among any vertebrates. It lasts for 18 to 24 months.
- Spiny dogfish can grow up to 5 feet. However, their average size ranges between 3 and 4 feet.
- They contain mild venom in their spine that they use for defense purposes.
- They live a long life, up to 80 years. This age is quite surprising for small sharks.
- Spiny dogfish are one of the most widespread shark species. They mainly live in the Atlantic and Pacific oceans.
- They mostly live at 1150 feet. However, it can go up to 2500 feet as well.
- They are amazing swimmers. They can travel thousands of miles. It is a record that they have traveled 5000 miles. They migrated from Washington State to Japan.
- Females reach reproductive maturity between 12 and 20 years. They can also take 35 years to become fully mature. Males take 10 to 12 years.
- They are efficient predators. When they are moving in school. A spiny dogfish school can wipe out an entire school of herring or mackerel.
- They are usually harmless to humans.
- They are a model vertebrate in labs to study vertebrates’ anatomy and physiology.
In Summary
Spiny dogfish are small sharks and live in groups that comprise thousands of spiny dogfish. They fit in large public aquariums due to their size, aggressiveness, activity, and pack size. They prey on medium-sized fish and other invertebrates and lie at the tertiary level of their food chain. They behave differently towards humans and try to escape rather than fight. Sailors have numerous stories about them, as they have encountered them for thousands of years.
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