Marine Invertebrate Gallery

These pictures were taken of marine invertebrates sampled in Pleasant Bay in the summer of 2014. The species pictured are a selection of the over 80 species found. Photographs were made using a microscope at the Cape Cod National Seashore North Atlantic Coastal Lab

Crustaceans          Polychaete Worms          Bivalves          Other Invertebrates


Crustaceans

Caprella linearis Skeleton shrimp These alien-looking amphipods often attached by their rear legs to algae and eelgrass, and can be extremely abundant.

Caprella linearis
Skeleton shrimp
These alien-looking amphipods attach to algae and eelgrass with their rear legs and can be extremely abundant. People most often encounter them when pulling up their anchor.

Corophium spp. These amphipods build muddy tubes in mixed algae, often in estuaries and have distinctly larger second antennae.

Corophium sp
These amphipods build muddy tubes in mixed algae, often in estuaries and have distinctly larger second antennae.

Microdeutopus spp. This tube-building amphipod is often found in muddy and silty sediment, and has an unusually large first claw.

Microdeutopus sp
This tube-building amphipod is often found in muddy and silty sediment, and has an unusually large first claw.

Paraphoxus spinosus Hooded amphipod These amphipods bury and mud, and have a “hood” coming to a point over their upper antennae, with large dark eyes.

Eobrolgus spinosus
Hooded amphipod
These amphipods burrow in sand and mud, and have a “hood” coming to a point over their upper antennae, with large dark eyes.

Lysianopsis alba These amphipods burrow in shelly-sandy mud and have distinctly short, stubby antennae.

Lysianopsis alba
These amphipods burrow in shelly-sandy mud and have distinctly short, stubby antennae.

Haustoriidae Sand burrowers As their name suggests, Haustoriidae burrow in sandy sediment and have highly reduced sensory features with no apparent eyes – sort of like the moles of the sea!

Haustoriidae
Sand burrowers
As their name suggests, Haustoriidae burrow in sandy sediment and have highly reduced sensory features with no apparent eyes.

Ampelisca spp.   4-eyed amphipods.   These tube-building amphipods bury in mud and sandy environments and are extremely common in our samples, sometimes appearing in clusters of one thousand or more!

Ampelisca sp
4-eyed amphipods.
These tube-building amphipods bury in mud and sandy environments and are extremely common in our samples.

Unciola serrata This amphipod species tends to be larger than other amphipods, with a larger first claw and thicker, shorter second antennae.

Unciola sp
This amphipod species tends to be larger than other amphipods, with a larger first claw and thicker, shorter second antennae.

Idotea balthica This isopod clings to eelgrass and seaweed, and has a distinct telson (tail) shaped like curly brackets at the end.

Idotea balthica
This isopod clings to eelgrass and seaweed, and has a distinct telson (tail) shaped like curly brackets.

Edotea triloba This common isopod is found on muddy shores, pilings, and decaying eelgrass.  It looks similar to a trilobite fossil as its name suggests.

Edotea triloba
This common isopod is found on muddy shores, pilings, and decaying eelgrass. It looks similar to a trilobite fossil as its name suggests. (mm scale)

Oxyurostylis smithi This unusual-looking cumacean with a short, oval-shaped body and a long narrow tail is found in shallow water in soft sediment.

Oxyurostylis smithi
This unusual-looking cumacean with a short, oval-shaped body and a long narrow tail is found in shallow water in soft sediment.

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Polychaete Worms

Lumbrineridae Opal Worms Opal worms live in mud and sand and beneath stones.   They often have a shimmering, glossy appearance that gives them their name.

Lumbrineridae
Opal Worms
Opal worms live in mud and sand and beneath stones. They often have a shimmering, glossy appearance that gives them their name.

Cirratulidae Fringed worms These worms burrow in mud and gravel and under rocks.  The long, stringy filaments on the body segments towards the head are gills.

Cirratulidae
Fringed worms
These worms burrow in mud and gravel and under rocks. The long, stringy filaments on the body segments towards the head are gills.

Capitellidae Thread worms Thread worms are found in sandy mud, and are often one of the first species to colonize an area that has been affected by pollutants.

Capitellidae
Thread worms
Thread worms are found in sandy mud, and are often one of the first species to colonize an area that has been affected by pollutants.

Syllidae These worms are often quite tiny and can be found under stones, shells, seaweeds, and other benthic organisms.  They are distinguished by their fused or partially fused palps (fleshy protrusions from the head) and three antennae.

Syllidae
These worms are often quite tiny and can be found under stones, shells, seaweeds, and other benthic organisms. They are distinguished by their fused or partially fused palps (fleshy protrusions from the head) and three antennae.

Streblospio benedicti Mudworms Mudworms build soft, mud-covered vertical tubes attached to shells and hard objects in shallow water.  They can be identified by their two long tentacles and two banded gills protruding from their head segment.

Streblospio benedicti
Mudworms
Mudworms build soft, mud-covered vertical tubes attached to shells and hard objects in shallow water. They can be identified by their two long tentacles and two banded gills protruding from their head segment.

Aricidea sp. Like many others, these worms can be found burrowing in mud, and can be easily identified by the single tentacle protruding from their head segment.

Aricidea sp.
These worms can be found burrowing in mud, and can be easily identified by the single tentacle protruding from their head.

Orbiniidae Orbiniidae live in mud and sand near low tide level.  Their parapodia (fleshy, feet-like protrusions) migrate from the sides to the ventral surface of the worm at the midsection, making the rear of the worm look “furry.”

Orbiniidae
Orbiniidae live in mud and sand near low tide level. Their parapodia (fleshy, feet-like protrusions) migrate from the sides to the ventral surface of the worm at the midsection, making the rear of the worm look “furry.”

Opheliidae These worms burrow headfirst into shallow sand, and have a characteristic groove that runs the length of the body.  These specimens tend to be more intact than many other worm species.

Opheliidae
These worms burrow headfirst into shallow sand, and have a characteristic groove that runs the length of the body. These specimens tend to be more intact than many other worm species.

Nereidae Clam Worms Clam worms are common in mudflats and sandflats where bivalves are also found, and often have a frilly-looking appearance with two pairs of eyes.  Some species can live inside the tubes of bamboo worms.

Nereididae
Clam Worms
Clam worms are common in mudflats and sandflats where bivalves are also found, and often have a frilly-looking appearance with two pairs of eyes. Some species can live inside the tubes of bamboo worms.

Maldanidae Bamboo Worms Bamboo worms live in tubes constructed out of sand grains cemented together.  Aptly named, these worms have long, bamboolike body segments and a hoodlike head.

Maldanidae
Bamboo Worms
Bamboo worms live in tubes constructed out of sand grains cemented together. Aptly named, these worms have long, bamboolike body segments and a hoodlike head.

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Bivalves

Gemma gemma Amethyst gem-clam These tiny clams are very common in sand and silty sand in shallow water, often numbering in the hundreds for each sample!

Gemma gemma
Amethyst gem-clam
These tiny clams are very common in sand and silty sand in shallow water. The individuals pictured are mature adults measuring 2-3 millimeters across. (mm scale)

Yoldia limulata File Yoldia This bivalve has a row of teeth on each side of the umbo (the “point” of the shell) which can be clearly seen in this picture.

Yoldia limulata
File Yoldia
This bivalve has a row of teeth on each side of the umbo (the “point” of the shell) which can be clearly seen in this picture.

Tellina agilis Northern Dwarf-Tellin These bivalves are common in fine sand and mud and have a distinct, asymmetrical oval shape.

Tellina agilis
Northern Dwarf-Tellin
These bivalves are common in fine sand and mud and have a distinct, asymmetrical oval shape.

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Other Invertebrates

Limulus polyphemus Horseshoe Crab This is a juvenile horseshoe crab, which needs to molt 16 to 17 times to reach adult size – up to two feet long from head to tail!  Horseshoe crabs are considered “living fossils” since they first appeared on this earth 450 million years ago.

Limulus polyphemus
Horseshoe Crab
This is a juvenile horseshoe crab, which needs to molt 16 to 17 times to reach adult size – up to two feet long from head to tail! Horseshoe crabs are considered “living fossils” since they first appeared on this earth 450 million years ago.

Ophiuroidea Brittle Star Like their seastar cousins, brittle stars use their arms to crawl across the seafloor.  They are also known as “serpent stars” for their long, sinuous arms.

Ophiuroidea
Brittle Star
Like their seastar cousins, brittle stars use their arms to crawl across the seafloor. They are also known as “serpent stars” for their long, sinuous arms.

Pycnogonida Sea spider Worry not, arachnophobes, these sea spiders are so tiny you’d never notice they are there, and they are not even true spiders!  This female is carrying a clutch of eggs that will soon hatch out even tinier sea spiders.   Because these spiders have such a high surface-to-volume ratio, they do not need lungs or gills to breathe – they can rely on direct diffusion for respiration.

Pycnogonida
Sea spider
This female sea spider is carrying a clutch of eggs that will soon hatch out even tinier sea spiders. Because these spiders have such a high surface-to-volume ratio, they do not need lungs or gills to breathe – they can rely on direct diffusion for respiration.

Nudibranchia Sea slug Nudibranchs are soft-bodied gastropods that can come in a wide range of colors and shapes.  This tiny nudibranch has soft, yellow spines that give it a bumpy appearance.

Nudibranchia
Sea slug
Nudibranchs are soft-bodied gastropods that can come in a wide range of colors and shapes. This tiny nudibranch has soft, yellow spines that give it a bumpy appearance and is a barnacle predator.

Strongylocentrotus droebachiensis Green Sea Urchin Green sea urchins can occur most commonly in rocky subtidal areas and the intertidal zone.  The urchin grazes on predominantly seaweed, and is eaten in turn by many marine animals (despite the spines!) including sea stars, crabs, and fish.

Strongylocentrotus droebachiensis
Green Sea Urchin
Green sea urchins can occur most commonly in rocky subtidal areas and the intertidal zone. The urchin grazes on predominantly seaweed, and is eaten in turn by many marine animals (despite the spines!) including sea stars, crabs, and fish.

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