calum'sfossils
Stenolaemata
Age: 343–337 Ma
Viséan
Middle Mississippian Epoch
Carboniferous Period - Giant arthropods and amphibians, early reptiles, most plants fern or lycophyte-like, known for tropical forests and seas
Paleozoic Era - pre-Dinosaurs
Location: Hurst Green (Stonyhurst)
Hodder Place
Stonyhurst Bathing Hut remains by the riverbanks of the Hodder
Rock Type: Rad Brook Mudstone Member within the Pendleside Limestone Formation
Species:
Bryozoa, also known as Polyzoa or Ectoprocta, commonly referred to as moss animals, are a phylum of simple aquatic invertebrates. Nearly all bryozoans live in sedentary colonies, and individual bryozoans, or zooids, are typically about 0.5 mm long. They feed using a specialized structure called a lophophore, a crown of tentacles that filters particles from the water, similar to the lophophore of a brachiopod.
Bryozoan colonies can take a variety of forms, including sheets, fans, or bush-like structures. Some bryozoans, particularly those with calcified exoskeletons, can resemble small corals. Though individual zooids are microscopic, colonies can grow up to 1 meter (3 ft 3 in), although most are smaller than 10 cm (4 in). The growth patterns of colonies depend on zooid arrangement and skeletal secretion, resulting in forms ranging from sheet-like to bush-like colonies.
The most common form of marine bryozoans is encrusting colonies, where a sheet of zooids spreads over surfaces, sometimes growing to over 50 cm and containing millions of zooids. These encrusting colonies often have calcified exoskeletons and a moss-like appearance, giving the phylum its name (from the Greek words "Bryon" for moss and "Zoon" for animal). Large encrusting colonies form "chimneys" to expel filtered water, avoiding re-filtering it.
Within each colony, individual zooids are specialized, with some responsible for feeding and nutrient distribution, while others perform functions like defence or egg incubation. Zooids consist of two parts: the cystid, which provides structural support, and the polypide, which contains the internal organs. Interestingly, when overloaded with waste, the polypides are discarded, and new ones are regenerated.
Bryozoans possess a U-shaped gut, with the mouth located inside the lophophore and the anus outside it. Most freshwater bryozoan zooids are simultaneous hermaphrodites, while marine species typically function first as males and later as females. All bryozoan species release sperm into the water; some also release ova, while others capture sperm via their tentacles for internal fertilization.
After fertilization, bryozoan larvae either settle quickly due to large yolks or swim and feed for a few days before settling. Upon settling, the larvae undergo a dramatic metamorphosis, rebuilding most of their internal structures. Freshwater bryozoans produce statoblasts, which can survive harsh conditions, ensuring the colony’s lineage continues.
Bryozoans are divided into three main classes: Stenolaemata (marine bryozoans), Phylactolaemata (freshwater bryozoans), and Gymnolaemata (mostly marine bryozoans, with some brackish water species).
There are approximately 5,869 living species of bryozoans known. While bryozoans were originally all colonial, some secondarily solitary forms have evolved, adapting to life in marine sands or deep-sea habitats.
The evolutionary relationships of bryozoans with other phyla, such as brachiopods and phoronids, are still debated. Both morphological and molecular studies differ on whether bryozoans should be grouped with these other lophophorate animals and whether they are protostomes or deuterostomes.
Bryozoan fossils first appear in the Early Ordovician, making them the last major phylum to appear in the fossil record. This suggests that earlier bryozoans were likely unmineralized and thus not well-preserved. Early fossils are typically of erect forms, but encrusting forms later became more dominant.
The Stenolaemata class includes exclusively marine bryozoans that first appeared in the Ordovician. These bryozoans were the dominant group during the Paleozoic, with many extinct orders forming important reef structures. The Cyclostomatida order, originating in the Ordovician and still extant, includes species with robust, calcified exoskeletons, making them well-represented in the fossil record.
Although stenolaemates declined after the Permian extinction, Cyclostomatida diversified during the Jurassic and became a major group of bryozoans in the Mesozoic, although they later experienced declines at the end of the Cretaceous. Today, cyclostomatid bryozoans remain important components of modern marine ecosystems.
Extant and extinct orders of Stenolaemata include: Cyclostomatida (Ordovician-present), Cryptostomata † (Ordovician-Triassic), Cystoporida † (Ordovician-Triassic), Esthonioporata † (Ordovician-Devonian), Fenestrata † (Ordovician-Permian), Timanodictyina † (Devonian-Permian), and Trepostomatida † (Ordovician-Triassic).
The term Bryozoa was introduced in 1831, shortly after Polyzoa in 1830. Later, a similar group of animals was discovered, and it was initially included in Bryozoa. However, in 1869, these were classified separately as Entoprocta, while the original Bryozoa became known as Ectoprocta. Though there were debates about these terms, "Bryozoa" is now the widely accepted name.
Stenolaemata
Age: 343–337 Ma
Viséan
Middle Mississippian Epoch
Carboniferous Period - Giant arthropods and amphibians, early reptiles, most plants fern or lycophyte-like, known for tropical forests and seas
Paleozoic Era - pre-Dinosaurs
Location: Hurst Green (Stonyhurst)
Hodder Place
Stonyhurst Bathing Hut remains by the riverbanks of the Hodder
Rock Type: Rad Brook Mudstone Member within the Pendleside Limestone Formation
Species:
Bryozoa, also known as Polyzoa or Ectoprocta, commonly referred to as moss animals, are a phylum of simple aquatic invertebrates. Nearly all bryozoans live in sedentary colonies, and individual bryozoans, or zooids, are typically about 0.5 mm long. They feed using a specialized structure called a lophophore, a crown of tentacles that filters particles from the water, similar to the lophophore of a brachiopod.
Bryozoan colonies can take a variety of forms, including sheets, fans, or bush-like structures. Some bryozoans, particularly those with calcified exoskeletons, can resemble small corals. Though individual zooids are microscopic, colonies can grow up to 1 meter (3 ft 3 in), although most are smaller than 10 cm (4 in). The growth patterns of colonies depend on zooid arrangement and skeletal secretion, resulting in forms ranging from sheet-like to bush-like colonies.
The most common form of marine bryozoans is encrusting colonies, where a sheet of zooids spreads over surfaces, sometimes growing to over 50 cm and containing millions of zooids. These encrusting colonies often have calcified exoskeletons and a moss-like appearance, giving the phylum its name (from the Greek words "Bryon" for moss and "Zoon" for animal). Large encrusting colonies form "chimneys" to expel filtered water, avoiding re-filtering it.
Within each colony, individual zooids are specialized, with some responsible for feeding and nutrient distribution, while others perform functions like defence or egg incubation. Zooids consist of two parts: the cystid, which provides structural support, and the polypide, which contains the internal organs. Interestingly, when overloaded with waste, the polypides are discarded, and new ones are regenerated.
Bryozoans possess a U-shaped gut, with the mouth located inside the lophophore and the anus outside it. Most freshwater bryozoan zooids are simultaneous hermaphrodites, while marine species typically function first as males and later as females. All bryozoan species release sperm into the water; some also release ova, while others capture sperm via their tentacles for internal fertilization.
After fertilization, bryozoan larvae either settle quickly due to large yolks or swim and feed for a few days before settling. Upon settling, the larvae undergo a dramatic metamorphosis, rebuilding most of their internal structures. Freshwater bryozoans produce statoblasts, which can survive harsh conditions, ensuring the colony’s lineage continues.
Bryozoans are divided into three main classes: Stenolaemata (marine bryozoans), Phylactolaemata (freshwater bryozoans), and Gymnolaemata (mostly marine bryozoans, with some brackish water species).
There are approximately 5,869 living species of bryozoans known. While bryozoans were originally all colonial, some secondarily solitary forms have evolved, adapting to life in marine sands or deep-sea habitats.
The evolutionary relationships of bryozoans with other phyla, such as brachiopods and phoronids, are still debated. Both morphological and molecular studies differ on whether bryozoans should be grouped with these other lophophorate animals and whether they are protostomes or deuterostomes.
Bryozoan fossils first appear in the Early Ordovician, making them the last major phylum to appear in the fossil record. This suggests that earlier bryozoans were likely unmineralized and thus not well-preserved. Early fossils are typically of erect forms, but encrusting forms later became more dominant.
The Stenolaemata class includes exclusively marine bryozoans that first appeared in the Ordovician. These bryozoans were the dominant group during the Paleozoic, with many extinct orders forming important reef structures. The Cyclostomatida order, originating in the Ordovician and still extant, includes species with robust, calcified exoskeletons, making them well-represented in the fossil record.
Although stenolaemates declined after the Permian extinction, Cyclostomatida diversified during the Jurassic and became a major group of bryozoans in the Mesozoic, although they later experienced declines at the end of the Cretaceous. Today, cyclostomatid bryozoans remain important components of modern marine ecosystems.
Extant and extinct orders of Stenolaemata include: Cyclostomatida (Ordovician-present), Cryptostomata † (Ordovician-Triassic), Cystoporida † (Ordovician-Triassic), Esthonioporata † (Ordovician-Devonian), Fenestrata † (Ordovician-Permian), Timanodictyina † (Devonian-Permian), and Trepostomatida † (Ordovician-Triassic).
The term Bryozoa was introduced in 1831, shortly after Polyzoa in 1830. Later, a similar group of animals was discovered, and it was initially included in Bryozoa. However, in 1869, these were classified separately as Entoprocta, while the original Bryozoa became known as Ectoprocta. Though there were debates about these terms, "Bryozoa" is now the widely accepted name.